This was made in order to use a screen lid on my reef tank and still be able to use corded powerheads that were inside the tank, while having the screen lid sit flush with the rim of the tank. Print with many walls and high infill in PETG or ABS to ensure it is strong enough and is reef safe. I have had these on my tank for ~6 months and no warping/sagging has occurred. If you want both right and left, make sure you mirror the .stl provided. Please do not sell my designs.