I made this holster to attach my airsoft WE Glock 18c with spare mag grip to my molle vest.
I highly recommend this design:
I choose it as this is the only one with active spare mag retention.
Please note that original design was made for 3rd gen of glock - since I use we gen 4 I had to model the grip element with hair dryer to get perfect fit. therefore if you decide to use my design you WILL need to file it a bit to make sure the outer contour fits your grip.
I made my design with 1mm space all around so hopefully you will not need to file a lot.
I sued small spring I had in my tool box but simple ball pen spring will work as well but you may cut if a bit.
Other than this you will need a metal pin c.5cm. bend its last 1cm at 90 degree and it should nicely block in the cut and flush with contour. I added a drop of hot glue to keep it from falling out during usage.
To attach the holster to molle I used two of these:
I tested in during day of airsofting and it served me well :) hope you will have fun with it - please post makes if you print one :)