Beer cozy, flexible by design

I wanted to make a cool beer cozy and had an idea how I could make a very flexible print even using rigid filament like PETG. This is the first result :)

Design

The whole point of the design is the corrugated outside wall.

If you print this in vase mode, even a rigid filament can flex, because a relatively large deformation of the wall results in minimal deformation of the individual thin filament strands arranged in loops.

These loops are also functional - the whole this wall is 5mm thick, but the filament only accounts for 0.4mm. This gives it good insulating properties - perfect for a beer cozy.

It is also slightly (1%) conical - this makes sure the cozy grips the can at the top, where the flexibility is the largest. At the bottom, it is slightly larger than the can diameter, so you can insert and remove the can easily.

Printing instructions

Slice the model in vase mode (this is critical) with 2mm bottom thickness (to make the transition to the wall at the right height for maximum flexibility.

I made it using translucent red PETG, but most other rigid filaments should work.

The sweet spot of the design should be at 0.4mm print width (grips the can nicely, is flexible enough, and not too heavy). Bigger print widths should result in a heavier, stronger, and less flexible cozy, while smaller ones should be lighter, but possibly not strong/grippy enough.

Size is just right for a normal 330ml can. I use the same one for the 500ml cans as well, but if you wanted, you could make a 500ml version by simply scaling the model in Z direction, diameter is the same.

A big thanks to Jože for the pics!