Quickdraw mod for 556 STANAG magazines.
How to mount:

Step 1: Print
Step 2: Remove back cover of mag
Step 3: Use template to mark drill-holes
Step 4: Drill two 5mm holes
Step 5: Push quickdraw attachment through holes
Step 6: Use vise grip pliers to keep parts together
Step 7: Melt pins
Step 8: Press the molten plastic flat
Step 9: (Optional) Paint
Step 10: Mount back cover

I recommend printing on its side for optimal strength