Plotter Hub

A few months ago I bought an AxiDraw compatible pen plotter but didn't want my Mac tethered to it for the whole plot. So I built Plotter Hub, a plot server that runs on a Raspberry Pi (a Zero 2 W or 3B+ is fine). Upload an SVG over WiFi, then start / pause / resume and monitor the plot from any device, with optional vpype optimization and physical pause-button support for pen changes between layers. Anyone with an AxiDraw-compatible plotter can use it — it's free and open source. Repo link and install instructions: https://www.synendo.com/plotterhub

Plotter Hub after receiving a 3 layer SVG file via GD Studio

Companion app: GD Studio

I also built a macOS app, GD Studio, for designing the artwork I plot — generative line-art patterns shaped with live sliders, plus layers for text and imported SVG. It exports plotter-ready SVG/PDF, but it can also send a plot directly to Plotter Hub over its API (with options for vpype optimization, plotter speeds, and pausing between layers). It's a paid app with a free trial.

One of the many patterns in GD Studio, combined with a text layer

https://preview.redd.it/jp47ef1ai0bh1.png?width=2560&format=png&auto=webp&s=d8f9c402a167d32146b2f39e42c8267ebcebd644

• Plotter Hub (free, open source): https://www.synendo.com/plotterhub
• GD Studio (macOS, paid + free trial): https://www.synendo.com/gdstudio

TL;DR: I built GD Studio, a Mac app for designing generative line art. It's aimed at people with a pen plotter, but you can also just play with the designs on screen without ever plotting. It exports SVG/PDF, or sends straight to a plotter via a little server I also made.

GD Studio is definitely a niche app. It's built for people who own a pen plotter — a machine that holds a real pen and draws your artwork on paper. GD Studio exports standard SVG, so it works with any pen plotter. If a plotter isn't your thing, GD Studio is still a fun sandbox for generating line-art designs on screen, but its whole point is producing something a plotter can draw. Posting here in case it reaches the few of you who'd like to try it out.

A few months ago I picked up a pen plotter and my first drawings were mostly mathematical patterns. I wanted one macOS app where sliders and settings directly shape the final drawing, instead of juggling websites and code snippets. Since I'm an iOS/macOS developer, I built it: GD Studio.

With GD Studio you can:

• Create generative pattern layers (with a shuffle button for quick ideas)
• Add text layers
• Import a photo and convert it into pen strokes — more on that below
• Import existing plottable SVGs into a layer
• Adjust stroke, dash patterns, render styles (wobble, dotted, nested outlines), masks, scale, rotation, and positioning per layer

And you set the paper size, orientation, and margins. The result exports as SVG or PDF.

One of the many patterns in GD Studio, combined with a text layer

The newest feature — photos into pen strokes: Add an Image layer, drop in a photo (from a file or your Photos library), and pick a conversion style. GD Studio reads the picture's light and dark and rebuilds it from continuous pen strokes and single pen-taps — never a flat ink fill — so the preview matches exactly what the pen draws. Brightness and Contrast sliders shape how the subject reads. Seven styles are available: Stipple, Halftone, Hatch, Contour, Outline, Sketch, and Squiggle.

Combined image styles in different pen colors

On the plotting side: GD Studio's standard SVG export means you can plot with whatever pen plotter and workflow you already use. On top of that, it can send a design straight to Plotter Hub, a small plot server I also built that runs on a Raspberry Pi so your Mac doesn't stay tethered to the plotter. Plotter Hub is for AxiDraw-compatible plotters specifically, and it's free, open source, and totally optional.

Plotter Hub after receiving a 3 layer SVG file via GD Studio

VisionTagger: some of you might remember VisionTagger, the macOS app I've shared here before for AI-generated image captions and keywords. Mentioning it in case it's useful to anyone who missed it.

Example of metadata generated by VisionTagger

More info

• GD Studio (macOS, paid + free trial): https://www.synendo.com/gdstudio
  • Price is a one-time purchase: $29.99 / €24.99
• Plotter Hub (free, open source): https://www.synendo.com/plotterhub
• VisionTagger (macOS, paid + free trial): https://www.synendo.com/visiontagger
  • Price is a one-time purchase with a discounted price: $24.99 / €19.99

Transparency: I’m Marco Henkes, indie developer at Synendo.

• LinkedIn: https://www.linkedin.com/in/marcohenkes/
• Contact: apps@synendo.com
• Website: https://www.synendo.com
• Privacy Policy: https://www.synendo.com/gdstudio/privacy/ + https://www.synendo.com/visiontagger/privacy/
• Terms of Service: https://www.synendo.com/gdstudio/terms/ + https://www.synendo.com/visiontagger/terms/

TL;DR: Last week I shared Plotter Hub — a free, open-source Raspberry Pi plot server for AxiDraw-compatible plotters — and its companion macOS design app, GD Studio. This week GD Studio got a new feature: importing a photo and converting it into pen strokes (stipple, halftone, hatch, and more) instead of a flat fill. Reposting for anyone who missed the first thread.

What's new in GD Studio: photo import

Add an Image layer, drop in a photo (from a file or your Photos library), and pick a conversion style. GD Studio reads the picture's light and dark and rebuilds it from continuous pen strokes and single pen-taps — never a flat ink fill — so the preview matches exactly what the pen draws. Brightness and Contrast sliders shape how the subject reads. Seven styles are available: Stipple, Halftone, Hatch, Contour, Outline, Sketch, and Squiggle.

Since it stays stroke-based, the SVG that reaches your plotter is genuine pen paths, not raster — so it optimizes and plots like any other line-art file.

Combined image styles in different pen colors

In case you missed it: Plotter Hub

A few months ago I bought an AxiDraw compatible pen plotter but didn't want my Mac tethered to it for the whole plot. So I built Plotter Hub, a plot server that runs on a Raspberry Pi (a Zero 2 W or 3B+ is fine). Upload an SVG over WiFi, then start / pause / resume and monitor the plot from any device, with optional vpype optimization and physical pause-button support for pen changes between layers. Anyone with an AxiDraw-compatible plotter can use it — it's free and open source, and works without GD Studio. Repo link and install instructions: https://www.synendo.com/plotterhub

Plotter Hub after receiving a 3 layer SVG file via GD Studio

Companion app: GD Studio

GD Studio is the macOS app I design with — generative line-art patterns shaped with live sliders, plus layers for text, imported SVG, and now photos. It exports plotter-ready SVG/PDF or sends a plot directly to Plotter Hub over its API (with options for vpype optimization, plotter speeds, and pausing between layers). It's a paid app with a free trial.

• Plotter Hub (free, open source): https://www.synendo.com/plotterhub
• GD Studio (macOS, paid + free trial): https://www.synendo.com/gdstudio

One of the many patterns in GD Studio, combined with a text layer

TL;DR: Last week I shared GD Studio, a Mac app for designing generative line art. This week there's a new feature: you can now import a photo and convert it into continuous pen strokes and single pen-taps. Reposting for anyone who missed the first thread.

What's new: photo import

Add an Image layer, drop in a photo (from a file or your Photos library), and pick a conversion style. GD Studio reads the picture's light and dark and rebuilds it from continuous pen strokes and single pen-taps — never a flat ink fill — so the preview matches exactly what the pen draws. Brightness and Contrast sliders shape how the subject reads. Seven styles are available: Stipple, Halftone, Hatch, Contour, Outline, Sketch, and Squiggle.

Because everything stays real strokes rather than a raster fill, an imported photo behaves like any other layer — you can combine it with generative pattern layers, mask it, scale and rotate it, and send the whole thing straight to the plotter.

Combined image styles in different pen colors

In case you missed the first post

A few months ago I picked up an AxiDraw compatible pen plotter and wanted a single macOS app where sliders and settings directly influence the final drawing. So I built GD Studio. With it you can:

• Create generative pattern layers (with a shuffle button for quick ideas)
• Add text layers, and now import photos as an Image layer
• Import existing plottable SVGs into a layer
• Adjust stroke, dash patterns, render styles (wobble, dotted, nested outlines), masks, scale, rotation, and positioning per layer

One of the many patterns in GD Studio, combined with a text layer

The result exports as SVG or PDF, or sends directly to Plotter Hub over its API — with options to optimize the SVG, fine-tune plotter speeds, and pause between layers. Plotter Hub is a Raspberry Pi plot server (free, open source) that lets you start / pause / resume and monitor plots over WiFi, so your Mac doesn't stay tethered.

• GD Studio (macOS, paid + free trial): https://www.synendo.com/gdstudio
• Plotter Hub (free, open source): https://www.synendo.com/plotterhub

Plotter Hub after receiving a 3 layer SVG file via GD Studio

TL;DR: I built GD Studio, a Mac app for generative line art, plotted through Plotter Hub, a Raspberry Pi plot server I also built. Plotter Hub is free/open source, GD Studio is paid with a free trial. Links at the bottom.

A few months ago I picked up an iDraw H SE A3 and my first plots were mostly mathematical patterns. . While working on those, I realized I wanted a single app where I could use sliders and settings to directly influence the final drawing. There are websites for specific patterns, and there are plenty of code examples available, but I wanted everything integrated into one macOS app.

Since I am an iOS/macOS developer, I built that app myself, with some help from Claude for the mathematical models. The result is GD Studio.

With GD Studio you can:

• Create pattern layers, including a shuffle button to quickly generate new ideas
• Add text layers to include text in your plot
• Import existing plottable SVGs into a layer
• Add a calibration layer to calibrate the pen between different layers

For each layer, you can further adjust the output, including:

• Stroke settings, such as color and line width, mainly to help visualize the final plot
• Dash patterns and render styles, such as wobble, dotted, and nested outlines
• Masks, to hide parts of a layer
• Scale, rotation, and exact positioning

And of course, you can set the paper size, orientation, and page margins.

GD Studio

Made with GD Studio

The result can be exported as SVG or PDF, but it can also be sent directly to Plotter Hub. Both apps were developed at the same time, and Plotter Hub has an API that GD Studio uses. Before sending the plot, you can choose whether Plotter Hub should optimize the SVG, whether the plotter speeds should be fine-tuned, and whether the plot should pause between layers.

Plotter Hub

• GD Studio (macOS, paid + free trial): https://www.synendo.com/gdstudio
• Plotter Hub (free, open source): https://www.synendo.com/plotterhub

TL;DR: I built GD Studio, a Mac app for generative line art, plotted through Plotter Hub, a Raspberry Pi plot server I also built. Plotter Hub is free/open source, GD Studio is paid with a free trial. Links at the bottom.

GD Studio

A few months ago I picked up an iDraw H SE A3 and my first plots were mostly mathematical patterns. While working on those, I realized I wanted a single app where I could use sliders and settings to directly influence the final drawing. There are websites for specific patterns, and there are plenty of code examples available, but I wanted everything integrated into one macOS app.

Since I am an iOS/macOS developer, I built that app myself, with some help from Claude for the mathematical models. The result is GD Studio.

With GD Studio you can:

• Create pattern layers, including a shuffle button to quickly generate new ideas
• Add text layers to include text in your plot
• Import existing plottable SVGs into a layer
• Add a calibration layer to calibrate the pen between different layers

For each layer, you can further adjust the output, including:

• Stroke settings, such as color and line width, mainly to help visualize the final plot
• Dash patterns and render styles, such as wobble, dotted, and nested outlines
• Masks, to hide parts of a layer
• Scale, rotation, and exact positioning

And of course, you can set the paper size, orientation, and page margins.

GD Studio

Made with GD Studio

The result can be exported as SVG or PDF, but it can also be sent directly to Plotter Hub. Both apps were developed at the same time, and Plotter Hub has an API that GD Studio uses. Before sending the plot, you can choose whether Plotter Hub should optimize the SVG, whether the plotter speeds should be fine-tuned, and whether the plot should pause between layers.

Plotter Hub

I didn't want my Mac tethered to the plotter for the whole job, so I built Plotter Hub, a plot server that runs on a Raspberry Pi (a Zero 2 W or 3B+ is plenty). I upload an SVG over WiFi and start / pause / resume and monitor the plot from any device, with optional vpype optimization and physical pause-button support for pen changes between layers. It's free and open source and can be used without GD Studio.

Plotter Hub

• GD Studio (macOS, paid + free trial): https://www.synendo.com/gdstudio
• Plotter Hub (free, open source): https://www.synendo.com/plotterhub

TL;DR: I got an iDraw H SE A3 but didn't want my Mac tethered to it for the whole plot. So I built Plotter Hub — a free, open-source plot server that runs on a Raspberry Pi. Upload an SVG over WiFi, then start / pause / resume and monitor the plot from any device, with optional vpype optimization and physical pause-button support. I also built a companion macOS app, GD Studio, for designing generative line art that exports plotter-ready SVG or sends straight to Plotter Hub.

Plotter Hub

Plotter Hub

A few months ago, I bought an iDraw H SE A3 pen plotter, and so far I've been very happy with it. It comes fully assembled, you can start using it right away, and the results are very precise. UUNA TEK regularly has special offers and discount codes, and with no shipping costs it was considerably cheaper for me than comparable models from other manufacturers. I'd recommend it.

There was only one downside: the plotter had to be connected directly to my Mac via USB. I wanted to keep the plotter in a different place from my computer, and I didn't want to depend on my Mac staying connected during the whole plot. Since the iDraw H SE A3 is compatible with AxiCLI, I connected the plotter to a Raspberry Pi 3. Now I can start a plot over WiFi and the Pi controls the plotter from there — my computer no longer needs to stay connected.

Sending commands manually worked, but in practice it wasn't ideal. So I built a web interface using AxiDraw Python — with a lot of help from Claude Code. Through the web interface I can upload an SVG to the Raspberry Pi, then start a plot, pause it, and monitor its progress. Before plotting, an SVG can be optimized automatically with vpype. The physical pause button on the iDraw H SE A3 is supported as well, which is especially useful for multi-layer plots — after changing a pen, I resume the plot with a single button press.

I called the app Plotter Hub. Anyone with an AxiDraw-compatible pen plotter can use it; a powerful Pi isn't required (a Zero 2 W or 3B+ is fine). The app is free to install, and the source is open. More info, the repository link, and installation instructions are here: https://www.synendo.com/plotterhub

Companion app: GD Studio

I also built a macOS app, GD Studio, for designing the artwork I plot — generative line-art patterns shaped with live sliders, plus layers for text and imported SVG. It exports plotter-ready SVG/PDF, but it can also send a plot directly to Plotter Hub over its API (with options for vpype optimization, plotter speeds, and pausing between layers). It's a paid app with a free trial.

GD Studio

Made with GD Studio

I like Apple Photos, but I’ve always found one part frustrating: search is somewhat useful, yet a lot of the labels it relies on are hidden and hard to manage manually.

So I built VisionTagger to make my Photos library more searchable with consistent titles, captions, and keywords — without uploading images anywhere.

It’s a macOS app for Apple Silicon that generates metadata fully on-device and can write it directly back to Apple Photos. Your images and generated metadata stay on your Mac, and there’s no subscription or per-image pricing.

It also works with folders on disk and can export to XMP, JSON, CSV, and TXT, plus optional Finder tags.

https://preview.redd.it/yg5ua34nx34h1.png?width=1516&format=png&auto=webp&s=2ca292fa745ef08a052f71ddee9a19a4d832ba84

Requirements: Apple Silicon (M1 or later), macOS Tahoe 26, and at least 16 GB RAM.

There’s a free trial for 100 images.

Price is a one-time purchase with a discounted price: $24.99 / €19.99

Website: https://www.synendo.com/visiontagger
Video walkthrough: https://www.youtube.com/watch?v=AIZ3BQHsUkY

If you use Apple Photos and try it, I’d really like to hear whether it improves search in your library, and what would make it more useful.

I like Apple Photos, but I’ve always found one part frustrating: search is useful, yet a lot of the labels it relies on are hidden and hard to manage manually.

So I built VisionTagger to make my Photos library more searchable with consistent titles, captions, and keywords — without uploading images anywhere.

It’s a macOS app for Apple Silicon that generates metadata fully on-device and can write it directly back to Apple Photos. Your images and generated metadata stay on your Mac, and there’s no subscription or per-image pricing.

It also works with folders on disk and can export to XMP, JSON, CSV, and TXT, plus optional Finder tags.

https://preview.redd.it/vwtavua3pyxg1.png?width=825&format=png&auto=webp&s=7b988c53717c5b82fe46818d1dfaa80054354ca8

Requirements: Apple Silicon (M1 or later), macOS Tahoe 26, and at least 16 GB RAM.

There’s a free trial for 100 images.

Price is a one-time purchase: $34.99 / €29.99

Website: https://www.synendo.com/visiontagger
Video walkthrough: https://www.youtube.com/watch?v=AIZ3BQHsUkY

If you use Apple Photos and try it, I’d really like to hear whether it improves search in your library, and what would make it more useful.

AI-tools were used to improve this post. VisionTagger is localized in 10 languages, for 8 of them AI-tooling was used.

If you have thousands of photos and can never find the one you want later, VisionTagger may be something for you.

It’s a macOS app for Apple Silicon that generates searchable descriptions and keywords for photos fully on-device using local AI, so your library becomes easier to search. Compared with cloud keywording tools, your images and generated metadata stay on your Mac, and there’s no subscription or per-image pricing.

It works with folders on disk and Apple Photos Library, and can write metadata to XMP, JSON, CSV, and TXT, plus Photos metadata and optional Finder tags.

https://preview.redd.it/oy11cfb0oyxg1.png?width=825&format=png&auto=webp&s=42d1fa3d5e79583e4f43016890dd0f11233d39d9

Requirements: Apple Silicon (M1 or later), macOS Tahoe 26, and at least 16 GB RAM.

There’s a free trial for 100 images.

Price is a one-time purchase: $34.99 / €29.99

Website: https://www.synendo.com/visiontagger
Video walkthrough: https://www.youtube.com/watch?v=AIZ3BQHsUkY

If you try it, I’d really like to hear what works, what doesn’t, and what would make it more useful.

Transparency: I’m Marco Henkes, developer of VisionTagger at Synendo.

• LinkedIn: https://www.linkedin.com/in/marcohenkes/
• Contact: apps@synendo.com
• Website: https://www.synendo.com
• Privacy Policy: https://www.synendo.com/visiontagger/privacy/
• Terms of Service: https://www.synendo.com/visiontagger/terms/