Work for a commercial HVAC company in an OPS role, definitely not a tech, but I'm in and out of the field enough to see what breaks and get a lot of feedback from the team.
One service tech was annoyed that he looked online for an OEM replacement for the Victor Tote Carrier tubes that were cracking and getting lost, but one didn't exist. He knew I tinkered with graphic design, so told me I should "just make one" as a joke. Couldn't stop thinking about it.
I already had an interest in 3D printing and design, so I picked up an X1C (wanted enclosure for future proofing for ASA for HVAC unit tags in sunlight), taught myself CAD, and designed a replacement tube insert and lid from scratch in PETG. Few iterative designs later, fits within a .4mm tolerance, has an inner lip at the top for easier removal, holds up to field use, and was told looks better than the original.
Old VS new in the 3rd photo.
Has anyone else gone the DIY route when OEM parts just don't exist? Curious how common this actually is in the trade and how many others did something similar.