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).

https://news.ycombinator.com/item?id=34339459 (157 comments)

https://news.ycombinator.com/item?id=27645605 (74 comments)

https://news.ycombinator.com/item?id=41989322 (106 comments)

Note that there's a version of it as a single page: https://lcamtuf.coredump.cx/gcnc/full/ which is a bit easier to reference.

Used it a lot as a guide when working on the Shapeoko wiki (which is now off-line), so maybe some of it survives in:

https://shapeokoenthusiasts.gitbook.io/shapeoko-cnc-a-to-z

which a couple of projects have copied (with attribution) and at least one company copied (w/o acknowledgement).

3D printing seems to have taken up a lot of this interest due to how much easier is to source and load filament and start a print and how good opensource slicers are as opposed to traditional CAM software.

One thing which has helped it be somewhat timeless is only covering mechanical and geometric considerations in detail --- rather than cover software specifics it off-loads things to the Wikipedia article on Computer Aided Manufacturing, which has seen a lot of edits since this page was first put up --- my own usage has gone from my first project:

- requiring that I make a font with a character which had all the text and markings of a caliper dial using FontForge

- Making G-code for that w/ F-Engrave: https://www.scorchworks.com/Fengrave/fengrave.html

- Making the G-code for a fixture and the balance of the design using a Flash file: https://github.com/Jack000/PartKAM

- sending the design using a Python file, bCNC: https://github.com/vlachoudis/bCNC

(ob. discl., I work for Carbide 3D)

These days, I'd just draw it up in Carbide Create: https://willadams.gitbook.io/design-into-3d/2d-drawing make toolpaths in that application: https://willadams.gitbook.io/design-into-3d/toolpaths and then send the G-code using Carbide Motion: https://willadams.gitbook.io/design-into-3d/machine-motion (other manufacturers have similar workflows or bundle commercial software such as CarveCo or Vectric, and of course, there's Autodesk Fusion 360 which has taken up just about all the oxygen for free usage) and I've moved on to making my own project using Open(Python)SCAD:

https://github.com/WillAdams/gcodepreview

That said, there are still some folks making new software: https://news.ycombinator.com/item?id=47638498 and FreeCAD's 1.1 release seems a big update (despite the new book _FreeCAD Beginner's Handbook_ being branded version 1.1 on the cover but telling one to download 1.0 or later and providing screengrabs and instructions for 1.0).