Debowler. Take a traditional metal dart and remove the tip with a vice. Heat tip slightly and press into the opening after applying a dab of superglue. Design works well with abs and also even better if you can coat this in epoxy. We fill slighly with water at the bottom after the epoxy is added so that the cashed material does not burn the other discarded material and cause a flare up. We have added micah power to the epoxy and other similar thing. Get as creative as you want. Good volume to the ash tray portion. If you are famililar with doing crystal petg prints this would also be very cool looking and have a more traditional ash tray look:) Enjoy