Airsoft Amplifier - Make Your Own

Literally just a 28mm diameter circle, 16mm deep, with a 14x1mm LH thread. Screws recommended, super glue might work.

Once you finish printing hold the adapter in the center of whatever cap you are using and trace the hole with a marker or pencil, cut that with a thin and sharp knife, X-ACTO knives work great. Screw the adapter to the cap, screw the assembly to the bottle, and live life loud.

Like with my r/speedsoft amp you may need to play with scaling or extrusion to get the threads perfect. If you have a nice printer it should work perfectly.
https://www.youtube.com/watch?v=abC1Y_VbeXs