Magnet advice

[Wayne]

Ok I built a acrilic L shaped box. Its 8"L X 8"L X 4"W X 1.5"D I will upload a picture after work. I plan on filling it with sand to place some corals. Its made from 1/4" Acrilic, and now I need to mount the magnets...

So how many magnets do you think I need? I was thinking minimum 4... should the magnets be inside the box (goes through acrilic and glass) or outside the box (goes though glass). Also I just used silicone for the box should I use epoxy to hold the magnets on?

TIA