There are only 2 things you will need:
1-Duct tape (I used digicamo, but any colour will do)
2-Your magazine (obviously)
Step 2: Making The Pulltab
All I did was split my duct tape in half and get 2 4 inch (10cm) strips of tape. I stuck it so that there is only about 1/2 an inch was stuck on the mag, then stuck it on the same way on the other side. I put the other strip over top to make it stronger. **Make sure that the pull-tab is long enough so that you can still crank the gear (if you have a wind-up mag)
Step 3: Finishing
To hold it in place I just wrapped some more duct tape around the bottom of the mag. And voila! You have a magpull!