Grimrock

The ones in the mod use the basic "lock" I think

there are no hooks for locks so I think you would have to use an alcove and rig it up to act like a lock

That would be why they don't work then

Thanks anyway.. next question though... if I'm using alcoves for this instead how do I make it so that the player can't simply pick the coins back up again?

You could on insert, destroy it.