I like insulated can holders to help keep a drink cool, and made a 3D-printable version!
The main tricky part in designing this was figuring out a way to make the can fit snugly without making it too tight. The problem with making something exactly fit a cylindrical object is that there is a ridiculously fine line between “too tight” and “too loose”.
My solution: crush ribs. (This is a well-known solution that allows for some tolerance variation in a manufactured object.)
Crush ribs are borrowed from the world of injection molding, but here I modify/misuse the concept a little. The three ribs on the inside of my can holder provide friction on the can to hold the can snug, but not TOO snug. Without them, the can would be too loose in the holder. But with them, it is just snug enough.
The author marked this model as their own original creation.