I took a tip from some of the electric people on securing their battery hatches.

I use the small magnets from Radio Shack to secure the doors, hatches, etc. on my planes. Imbed one (or more depending on the size ) in the door/hatch and one in the framework it sets into. If space for imbedding is at a minimum (such as hatches ) imbed a thin piece of steel in the hatch/door and the magnet (s) into the framework.

I have not had anything secured with the magnets come loose or off during flight, yet they are easy to open when you need access.