u/Due-Bell-6116

On my P1S, when I use PLA as interface support for PETG models, I always bump up the flushing volumes between these dissimilar filaments to avoid bond weakness from contamination.  I've been getting conflicting advice from internet and AI searches when doing the same on the U1.  

So, are  increased flushing volumes even necessary on a toolchanger that uses completely separate toolheads for each filament - is significant contamination even possible?  Some search results say "yes,"  but it appears that AI counts hits from Bambu forums as confirmation.  Many results say "no,"  Opinions or experience on this?  Thanks.

What are these commonly used 3D connectors called, and how can I most easily model these in my FreeCad or elsewhere to incorporated them into my own models. Are they standardized in anyway? They look like a kid's wooden train tracks. I've downloaded a couple of models that use these, and I like the tight connection often produced. Google search really hasn't helped me on this. Thanks for looking.

https://preview.redd.it/j6564p1he0yg1.png?width=692&format=png&auto=webp&s=f1714add3771c9a3f18982ce89b643014f3c21f0