I’m starting by trying to make a simple scissor linkage. The challenge is the rotating joint

I decrease the radius of the peg by 0.5mm compared to the hole. This gave me a nice fit. Slides smoothly, doesn’t pop out.

Hmm Only for the center hole though. The other’s are much too loose.

took about 1:10 to print 8

took about 12 mins to print 1

0.3 is definitely too big

0.4 is nice and tight. But it isn’t good enough. The thing still wants to get out of the hinge.

Back to the drawing board. A three piece design? Or just make the pegs and holes longer?

Update: I extended the holes so the diameter equals the length. It works GORGEOUS.

I printed a circular version. You just need to angle the bars of the scissor by 2 *pi/N where N is the number of sides of the polygon you want.