I’ve made a couple of these 3d printed magazine pouches and I am currently using it. It is designed to hold tanfoglio 9mm small frame magazines, I think it should work with lots of other brands, the max width of the magazine is 21mm and the depth can go from 31.5 to 35mm. The depth is adjustable so you can change the pressure over the magazine. it has a pinion system that allows you to rotate the pouch freely and lock it in place with a screw.
This is designed to work with a wide belt like the ones used in practical shooting, 7 or 8 mm, by 40mm.
you should buy
4x M3x30mm screws
8x M3 nuts
1x M3 nylock nut
3x M3x15mm screws
1x M3x20mm screws
You should keep in mind that nylock nuts are not completely standard so you may have to fiddle with the adjustment or glue it in place, it goes behind the movable part so the pressure screw screws on it.