this is my first-ever self-designed print and I'm really happy with how it turned out! I learned how to make it from this video: https://www.youtube.com/watch?v=hUt2W58YuEo the math is a lot more complex than I thought!

printed on a Creality Ender 3 V3 SE using basic PLA, no fancy settings or anything.

Instructions

1. I highly recommend printing two pieces, doesn't matter one peg or two peg, and snapping them together to see if your printer prints them adequately. my joins snapped together quite satisfyingly. If yours come out differently, I've included the .obj files for you to tinker with.
2. Print eight one-peg trusses and eight two-peg trusses. If you're like me and your fine motor skills aren't too good, print nine of each instead so you have a backup. On reflection I could've opted to put all three pegs on one side but I didn't /shrug. if anyone requests a three-and-zero version, I'll whip one up for you :3
3. arrange the two-peg trusses in a circle so that the obtuse angles are pointing counterclockwise. attach the one-peg trusses on top of that in a circle so that the obtuse angles are pointing clockwise. everything should snap together nice and easy.
4. pinch two points on opposite sides of the circle and press together or pull apart. I find it's easiest to do from the inside of the circle and pretty difficult to do from the outside. If the mechanism expands and contracts, success! You've got yourself a hoberman mechanism.