Place rare earth neodymium magnets (the super strong chrome looking ones) as shown. Then slide them together at same time.
These were tiny 6mm magnet cylinders from K&J magnets store. I had to double up and use two per side to make it easier.
Slightly larger magnets would have worked even easier. I have some 1" cube N52 that make it even easier, but i wanted to see how small I could go. A single 6mm cylinder on each side might barely work if you practice...but just stack a couple and you're good to go.
Placement matters. The magnets still still stick on the DVD case of you switch sides, but they won't unlock it.
Bottom of red padlock side = top left.
Top of red padlock = bottom right.
Worst part is pinching your fingers with N52 magnets: very painful 😖
...and here are a couple, slightly larger magnets I sunk into a hunk of scrap wood. Works great:
