I only have a single extruder printer, so I wanted to take the original fallout Nuka Cola cap model by ZR and turn it into something I could carry with me. This design works well for single extruders because you can add a pause at layer 30 and swap to white filament. 

I printed with 100% infill. This uses like under 2g of filament so it's a great last meter print. EDIT: I added a v2 with a larger keyring hole, as when I tried to go put this on my keychain, the rings I was using were too thick to support the original remix I did. Listed in the files as v2.