Dimensions of 10g shelf (left)
45"L X 40.5"H X 11"W
Can hold 6 10gallons total
Dimensions of 5G shelf (right)
35"L X 40.5"H X 11"W
Can hold 6 5G total
I'm not sure what size boards Nana cut them from, but atleast 11" wide and 1.5" thick.
before you make these though...be sure you have the space, and the proper outlets. Don't piggy back powerbars, all of my tanks, heaters, lights, pumps are hooked into 2 huge home theater powerbars that have 12 outlets each. PIggybacking powerbars is a serious fire hazard. So I just bought two of the biggest I could find, and plugged them into the wall, then everything for the tanks into the power bars. You may want to consider labelling cords (it's insane). Also, keeping the cords and outlets dry is a must (I set towels down when I do changes). My shelves sit on the floor itself, but it'd be easy enough to make them have an inch or two of space, simply by adding 2" to the height and then screwing the bottom board in so it's not flat on the floor.
Also, I've calculated that even if I had a full 12 tanks + lights, heaters, pumps, w/e...the wattage of the outlet can take it, so you don't have to worry about that.