Design question: what are these things called!?

I’m working on making some lens filter inserts (Bahtinov masks–useful for astrophotography) that can be easily popped in and out, and am using these integrated springy fittings with strain relief that I’ve seen and used before…but I have no idea what they’re called, so I’m having a hard time finding info, suggestions, reference materials, alternative designs, etc.


I’d appreciate any names for them, links, your own experience and suggestions for designing them…whatever you’ve got. (I’m fairly sure Dan posted something a while ago that included some design tips for them, but I haven’t been able to find that, either.)

I would call these “flextures”

Also, I love the fact that with this kind of mask, you are getting diffraction to work for you.


They’re definitely a type of flexture/flexure, but I think there might be a more specific term for this type of edge-cut flexture for friction-fit components.

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Is the joint called a torsion snap joint?


Ooooh–that’s certainly the right direction. Searching for “torsion snap joint” and subsequently “snap-fit joint” turned out some interesting and relevant results, including a Hackaday article from 2 days ago! (I’d lapsed in my Hackaday reading, so that was a good kick to get me back.) I still feel like there might be an even more accurate term, but I think the resources I’m finding now are most of what I’m looking for.
Thank you, @dklgood!


I don’t think it’s a form of snap joint but more a pressure joint. Radial pressure joint?


I’d agree, semantically, but didn’t have much luck using “radial pressure joint” (or variants like “laser cut pressure joint”) as a search term.

I quite like the name

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