Thought I would post this for you guys. Not my idea, I got it form Joe Greenley at Redfish, If you want step by step shots Google "redfish livingston 420" I know Joe posted picks here about that boat a while back.
Anyway here is my rendition, the textured shelf liner is a perfect epoxy barrier, it is self adhesive and leaves a very nice finished look. Only one thing make sure to clean off your magnets I got in a hurry and did not notice the red dots the magnet supplier put on mine until it was too late, now it’s under glass.

I used 3/4" x 1/16" magnets in the lids, and 3/4" x 1/8" in the hatch lips, about 2" apart. I would consider this an expedition setup. I have not installed the gaskets yet but will have no problem sealing these, seeing that you could loose a finger if you are not careful putting the lids on. SNAP! I am going to use a webbing loop tab at one edge to open these and it will be necessary.
Enjoy. Joe