Shotgun tracer to mount on a TM M870 Breacher. Fits tight over the barrel and shelltube-screw. Off course, you have to get the tube, electronics, tracer, to work with this. This design is made for the TM tracer models. (not the B&T) Check the 'Shotgun Tracer: Making off' photo album on https://www.facebook.com/blarock86cd to see how to make it. I only ask to leave the design as it is. No modifications. Off course, you can design your own base for different shotguns, or make another kind of tracer-support.Check the 'Shotgun Tracer: Making off' photo album on https://www.facebook.com/blarock86cd to see how to make it. You have to know some soldering skills, and be aware of the High-voltage!! on the yellow capacitors. Housing and base were printed with 25% infill and 1mm (3 layers) perimeter. Don't be cheap with these settings. This is the BB-shield :P