This is a pretty simple bottle opener keychain I designed for my father for Father's Day. The silhouette should be easily recognizable to any gun enthusiast. Both models are fully functional, but if you choose to use the model without a coin, make sure to use a hard and resilient material. (The model in the picture was made from Colorfabb XT. ABS for example would not work well as the teeth of the cap would cut into the plastic.) The model that uses a coin takes a US penny and can safely be made with something like PLA. Be sure to post pictures if you make one and leave feedback below; happy printing!
IMPORTANT! I highly recommend printing with 100% infill! Even with very thick walls, both models have the potential to break with anything less.
The models pictured were printed with clear Colorfabb XT for the coinless model and black PLA for the coin model. (For the coin model, it's been tailored to fit a US penny (printed with an Ultimaker 2). The coin should obviously fit very snugly and require a lot of force to initially set. If your coin falls out, try using a larger one and sanding the gap until you can just barely fit that coin in the gap.