Step 1: The problem and the solution
I have seen the things for sale, and for a hundred bucks, they will sell you essentially a closed box with a power strip in it. I can do that for less than $40. Want to watch?
Step 2: The initial materials
Step 3: Cutting the holes for the cords
On the second hole, I have a 2 inch hole saw and a 2 inch grommet. Guess what, though. The two inch hole saw is internal diameter, not external. The kerf of the blade makes the hole too big. A little silicone glue and it is fine.
If you notice, I cut down the grommet for the 1.5 inch hole, but not the 2 inch. The 2 inch grommet has a spring inside to flip the little plate it contains over. I didn't want to mess that up.