you can put screen from home depot around the eggcrate. I think a 4x2 eggcrate is like $11 from home depot. just wrap the screen around the eggcrate and throw a rubber band across the sides at top and bottom. I used the eggcrate for my pond filter, just be careful cutting it with snips, the little fragments like to go flying off between each little square which will leave gaps. they also sell clear plastic for drop ceilings which are 2x4 sheets. You would just have to drill your own holes, keeping it in place is the only problem unless you have sleeves for the sides and some type of clamp to keep it from slipping allowing larger fish to get in. Good luck !

cant wait