This week’s selection is the Chapstick Keychain Cap by Thingiverse contributor mike_new.
This is exactly what it appears to be: a replacement cap for your chapsticks, which just happens to be attached to your keychain.
Evidently mike_new was persistently losing the caps from his chapsticks and realized it would be a simple matter to create a solution through 3D printing. The replacement cap has a loop to attach to any keyring.
I like this design because it is simple and solves a real-world problem. I certainly wouldn’t want to walk around with an uncapped chapstick lubricating the inside of my pants pocket, and neither would you.
Since you’re doing the 3D printing of this object, you can fine tune the size of the cap to ensure a very solid fit on the slippery chapsticks you happen to be using.
One consideration I must mention is that of food safety. While you’re not ingesting food directly from this object as you might with a 3D printed cup, say, it is possible for the chapstick material to touch the cap in some cases. Normally, the chapstick material will not touch the cap, but you never know for sure. Take appropriate precautions.