***Updated 11/17/25 - Realized the threading did not have the optimized clearance. Corrected this issue so the top and bottom should thread together easier.

An adjustable 3D-printed stacking aid for mugs and glasses.
The geared arms expand evenly as you twist the top, allowing you to safely stack cups of the same size.
Available in two versions:

• 72–105 mm (large)
• 52–85 mm (small)
  No glue needed — just slide the gears in and screw the top and bottom piece together

The design uses interconnected geared arms that expand or contract together as you twist the top.
Just place it on top of your mug or glass and gently tighten — the arms will grip the rim evenly, letting you safely stack another mug on top.
The mechanism keeps everything centered and stable.

Two size options are available:

• Large version: fits cups 72 mm – 105 mm in diameter
• Small version: fits cups 52 mm – 85 mm in diameter

Ideal for standard mugs, tumblers, and many glass types.

Assembly

No glue required!

• The gears slide into place within the base.
  • The arms should all be in the same position/angle
• The top and bottom sections screw together to hold the arms in alignment.
• Once assembled, it’s ready to use immediately.

You can print all parts without supports, and assembly takes under a minute.