I used to drill holes in drip plates. Normally I would make a 1" square grid, drill all the intersections and the middle of each square with a 3/16" bit. I usally go small and enlarge the holes if need be.
I got lazy and I started using this
Its sold at any craft store or walmart. Ita called needle point.
With a felt or poly pad on top it makes a perfect drip pattern. I have a small series of drip trays in a trickle tower. Close to the dimensions you mentioned. I run a mag 9.5 and all the flow goes through this mesh, I even doubled up on return pumps pushing 1700gph at 0 ft and the mesh handled it just fine.
Its a great alternative to drilling thousands of tiny holes. Just my $0.02
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