How to lock/keep growing box door shut?

Ok, since a pc case is too small for my grow I have decided to build a grow box. I have got all of the dimensions and things and it is ready to cut out. But, the only thing I cannot think of is how it will stay shut.

I do not really want a lock on it because that would be obvious that theres something there. What else can I use? Please help.

multiple things:

Lock ( on a side so its not visable)
Latch (by anywhere cabs r sold)
Magnet type on inside of door and inside of CAB
Velco
Hell, you could even use some of your sticky'est ICKY!....maybe

Dude, the possibilities are endless :P
Goodluck