it’s the "impossible" spiral illusion that looks like one piece of plastic is literally melting through the other. It’s a simple print, but it’s honestly one of the most satisfying things you can have on your desk.

I designed this Spiral Passthrough to be a quick, easy print that works right off the build plate without you having to spend an hour sanding down the threads.

The Details

• The Fit: I’ve dialed in the tolerances so the inner piece slides through with just enough resistance to feel "smooth" rather than loose and floppy. (I also have higher and lower tolerance versions)

• Zero Supports: You don’t need 'em. The angles are steep enough to print clean on any decent machine.

• Visuals: It’s basically a fidget toy that doubles as a desk sculpture.

Tips for a Smooth Slide

If you want that "air-cushion" feel, keep these things in mind:

• Layer Height: Stick to 0.2mm or thinner. If your layers are too thick, the pieces will "click" against each other instead of sliding.

• Check for Blobs: If your printer over-extrudes a bit, you might have some bumps on the surface. A quick scrape with a hobby knife or a 2-second pass with some sandpaper will make it glide perfectly.

• Filament Choice: If you have any Silk PLA, use it here. The way the light hits the curves as it spins is half the fun.

If you end up printing one, drop a Make! I love seeing these in dual-colors or weird filaments. If the fit feels too tight or too loose on your printer, leave a comment and I’ll look into tweaking the files.