I really liked jijimath's locable present ornament, but I wanted to be able to fit a gift card in it. The only thing that has changed is the length of the fancy bow, the bottom and top of the box. The lock, lock socket, key, and part one of the bow are the same from the original version.
I printed the smaller bow at 101% the original size, and the larger bow 102% the original size and I got a really nice fit.
You may need to run the STL's through Netfabb first.
For support I did 2mm spacing with rectangular pattern, which worked great.
I printed all of these objects with 100% infill. It is especially important to increase infill for the lock socket, with has parts that are easily breakable.