I just finished building a lid for my buddys tank who also had FF's getting out with his screen lid. What i did was make the whole thing out of hardwood and cut 2 slots for the lighting fixtures and used a router on the edges so thay could drop in about 2/3 of the way into the lid with a Metal screen cover under it, second what i did to help air ventalation was drill 2 holes for 2 PC fans one on the far left and right that also drop 2/3 into the wood and sealed them in place, the next step was to run a section of 2" PVC pipe from one fan to the other attached to 2 PVC elbows and sealed them to the outside frame of the fans. The right fan blows the air out of the tank and the left draws the air into the tank. If thee FFs make it passed the screen and survive 2 fans thay find themselvs on the otherside of there prison

. This weekend we are thinking about cuting down the PVC pipe and adding a custom box to house a Hepa filter in the middle and possably drill a couple 1/16" holes in the return half to allow a small amount of fresh air to be drawn in as well. We tend to overthink alot but hell lol, thats half the fun ...