This is a trigger pull attachment for the Shahe Pull Tester. You need to provide one M6 nut.

trigger_pull_01.stl file: rotate this 180 deg so that the pins look up and print %100 infill, no supports. trigger_pull_02.stl file: print this with %100 infill and supports enabled. after the print, use a hair dryer and heat the bottom part and push the M6 nut in. It needs to be a tight fit. Then enlarge the holes a bit with a drill bit, use super glue and join both parts.