Discussion

Hobby CNC machining and resin casting

jwr: This guide is legendary. It helped me to learn and follow the process, and I made some pretty successful parts. For example, my own keycaps for all keyboards that I use: much larger than usual (for my large fingers), with a pleasant gently matte texture, in beautiful colors.Polyurethane resins are an amazing achievement, and very much underrated. So are platinum-cure silicones. With care, you can get design-to-parts precision of ±25μm, which is spectacular (and a bit surprising, too). The fact that modern polyurethane resins (Sika Biresin F50) have essentially zero shrink helps quite a bit, too.Incidentally, there is a whole bunch of youtubers doing casting using epoxy resins, or cheap silicones, there is a large following, but this is not representative of what the techniques really allow.If you want to step up from 3d-printing, this is the way to go! Especially given the proliferation of inexpensive desktop CNCs with really good precision (Makera and others).

jacquesm: Those resins are absolutely fantastic but do read the MSDS and be very careful, it doesn't take much to get yourself in the emergency ward with that stuff. Another risk to be acutely aware of is that these reactions usually are exothermic and can go runaway faster than you can blink of the conditions are right.