Hey Eki. It's 1/8 " plywood (luan, I believe). Yep drilled 'em all. what a nightmare. 420 pilot holes ( I stacked the two pieces together). Then because my paddle bit would've ripped it up, I decided on a hole saw, oops, I don't have the right size mandrel! So I get out my 1" forstner bit, cleaner cut anyway. Problem was that it wouldn't cut through both layers so, each hole twice. More than half the holes then had to be dug out of the tool Yeah 1, 260 holes drilled out today! I never even counted till it was done. The size was determined by available desk space without considering capacity at all.
Well worth the time, getting more space with my paints more in reach will help me enjoy paint time more.