For a single dummy AA battery: - 1 pc M6x50 mm countersunk bolt - 1 pc M6 nut For the externally powered dummy battery: - 1 pc M6x30 mm countersunk bolt - 1 pc M3x10 mm bolt - 1 pc M3 washer - 1 pc DC 6V ?A external power source (?A depends on the power hunger of your device) The assembly process is dead simple: 1. Dummy battery Put a nut to the top and screw in the M6x50 mm bolt into it. AA battery specification says: An AA cell measures 49.2–50.5 mm (1.94–1.99 in) in length, including the button terminal—and 13.5–14.5 mm (0.53–0.57 in) in diameter. The positive terminal button should be a minimum 1 mm high and a maximum 5.5 mm in diameter, the flat negative terminal should be a minimum diameter of 7 mm.[1] - so an M6x50 mm bolt will be perfectly fine. 2. Powered battery This piece of plastic comes with M3x0.5 mm and M6x1.0 mm threads. Depending on your print quality you may need to check the threads before assembly (just drive thru the proper threading tool on them) . Drive through the power source wires on the internal shafts and screw in the bolts to fix those wires. For more stable lock I advice to use an M3 washer underneath the M3 bolt. I recommend to print the threaded part with 0.1 mm layer height but 0.2 mm still will be fine if you will fix the threads with a threading tool after the print.