Mounting arm for optical mount PM1 type

This is a PM1 style mounting arm for a lens / prism / mirror optical mount. The arm is 3D printed, but also requires a 1.25" long 6-32 standoff (internally threaded, 1/4" O.D.) It uses a brass thumb screw on the rear with an 8-32 thread. The thumb screw hol requires threading before use.