3d
From Wiki2
3d
https://www.3dhubs.com/knowledge-base/collection/design-guidelines/
https://www.3dhubs.com/knowledge-base/how-design-snap-fit-joints-3d-printing/
http://web.mit.edu/2.75/resources/random/Snap-Fit%20Design%20Manual.pdf
https://www.youtube.com/watch?v=x-9g0joZ29k
http://fab.cba.mit.edu/classes/S62.12/people/vernelle.noel/Plastic_Snap_fit_design.pdf