M4 / AR15 / M16 Type Mag Horizontal Holder

So i have combine a Mag project that we are working on, with a thing I saw online the other day - The IDF uses a horizontal mag holder that slides into the mag well of their M16/M4/AR15. So i figured, i want one!
This is a work in progress - i am considering doing a double mag version, if i have tested this one and the weight seems decent. i will also further modify it, at a later stage, so swivel like the IDF version. I have left an m4 size nut and bolt space to secure the mag in it, just