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Material: PLA
The green version was printed 1:1. The purple version was scaled 50% larger. Note that I used a low end 3D printer for these parts which didn't hold the dimensions very well. With that, I needed to sand down the opening in the purple version by ~ 0.03" to allow the tetra to fit inside. If this happens to you, I suggest reprinting the tetra at a slightly smaller scale.
More Info: https://www.instructables.com/id/Caged-Tetrahedron-Puzzle/
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