These pockets have been made with two layers - the magnet is now housed, hidden, between these layers.
Step 1: Prep
Then I cut a small hole in the edge.
I made sure I had two magnets and wanted to experiment with placement.
I used Hard Disk Drive magnets. I was very careful to never let these magnets get too close to each other because the magnetic force is too strong and will break the magnet up into little pieces. I have done this magnet trick again using significantly weaker rare earth magnets and the quality is very poor. I recommend finding HDD magnets if you need this clasp to be secure. If you tried to pick pocket this pouch/pocket I would feel it because you will be lifting my whole utility belt, not just the flap of this individual pocket.
Step 2: Sewing
Pop the magnet in, place it and sew around it.
The trick here is patience. Remember you are sewing a magnet with a metal needle. Breath in, Breath out.
Step 3: Finishing
The only con with magnet fasteners that are as strong as this is walking past things like cars, fridges and work benches. Since this pocket sits on my hips I am forever being stuck to things. Bonus is I know that it works!