A modified mil spec(1.14" ~= 29mm) buffer tube for airsoft, with a slot for cables for rear wired AEGs. Fitment is dependent on your machines tolerances, some sanding might be needed.
You will need a rear screw and plate for mounting.
Print in standing orientation (thicker part on the plate), no need for support. Recommended to print with stronger materials, and heat resistance is recommended if you plan to use it in warm weather.

THIS IS ONLY FOR AIRSOFT TOYS, NOT REAL GUNS!