The_Critic posted...
make an original locking device for the final puzzle. You know those wooden puzzles with a square / rectangle inside a frame only 1 way? Id make one of those. When assembled, it pushes out the latches allowing the safe to open.
the puzzle pieces are hidden behind other puzzles, so you collect the puzzle pieces to solve a unique puzzle for the final prize.
that feels master thief to me.
That's a great idea, I don't really know how to put that into practice though.bdeginiteky gonna look into that though.
Edit: Don't know how to make, I should say.