The TrustFire X8 is the most recommended light source for GuerillaBeam projectors. This adapter creates a very strong connection to the flashlight. It's easy to print too. See https://gbeam.de/products/adapter-for-trustfire-x8-flashlights/ for additional details. Update 2015-05-16: New revision 4 Improved fit and printability. Increased length to reduce creep when hot. Also reduced the stress on the 'hinges' for easier assemby with less danger of inadvertently breaking the adapter.Printable with 0.8mm wall strength and 0% infill. For best results print with 0.1mm layer height and 100% fill. No support material is needed.