Decided to make a new screen top. This time, instead of using whiteboard, I used corrugated plastic. Two layers to sandwich the screen which is hot-glued together.
Here it is on the floor, and on the tank. Mind you I can not push the new lid down all the way into the groove because of the powerhead wires. I didn't cut notches in this top, because tomorrow I will no longer have the wires on the inside of the tank.