Requires a 3" long #10-24 bolt and nut. (which can be purchased at any hardware store)
This is a coupler designed for MAGPUL PMag30s and PMag40s but will also work for almost any other type of ar-15 magazine.
It is very important that you print this with at least a 70% infill. If you use an infill less than this you may experience cracking along the middle flange while cinching down the bolt and nut.
If you are printing this part in ABS you can give the two objects an acetone bath for increased strength and better aesthetics.
If you are experiencing cracking when tightening the nut and bolt you may need to increase your infill.