Design Guidelines for Snap Fit Joints


I want to print parts that can be assembled. I have no mechanical engineering background so I didn’t even know the relevant terminology. After a bit of research I learned that one way to do this is with snap-fit joints. I looked for design guidelines online on Google and amazon, figuring there must be well-known rules for how to design joints that are strong and reliable.

I found these great free PDFs, all by chemical companies:

These books also seem to contain a lot of useful information (according to their amazon previews), but they probably go well beyond what I need, and they’re not cheap:

Feel free to recommend others if you know any.

Retro Form 1+ Guide

Yes, follow these guidelines and your prints should come out more predictably as well.

Good luck!


The challenge with snap fit joints is that the current generation of resin gets very brittle as it cures.  When it’s still “fresh” a well designed joint can and will work (I’ve done plenty), but after a week or two of continued curing, the joints will typically break.  A “snap fit joint” requires the material to flex, just a little, but flex all the same, and well cured Form Labs resin does not like to flex at all.