What do you use to replace a screen on the top of an enclosure? It’s an 18x18x24 and is a split one with a plastic piece between the two sides. The silicone piece holding in the screen to the middle part is falling apart and I think the middle piece is also bent a little, though screen appears fine.
You can repair this using rtv.(room temp vulcanisation)[aquarium sealant] It has a very high temperature rating, remains flexible and after curing is safe to use around animals. Comes in multi colors from clear to black including red and blue.
The downside is it will need a few days of cure. It smells strongly of vinegar when first applied. It cures even at cold temperatures and isn’t affected by moisture. So, you can cure it outside to avoid the smell in the house. Lasts for years.
If you want to go a totally different direction or if you have a top which isn’t fixable, here’s a possible solution. My hubby constructed totally snug, escape proof lids using wooden tomato stakes and window screen/mesh from the local hardware store. Took a few nails for the stakes, hot glue for the screen. Cost almost nothing, didn’t take long. Please excuse the current barrenness. The female who lives there is soon to lay and I don’t want her tempted to do it anywhere besides the nest box.
This one also got a sheet of plexiglass because the cat kept wanting to sit on it. (The snake who was in there at the time didn’t mind.) We tried to keep him off, but wanted to ensure that he didn’t tear the mesh.