1 sheet of 3/4 inch plywood. I used a 5x5 sheet and cut it in half.
Shaper Origin
Orbital Sander
There are a few design details that can be suited to your taste. For my standing desk, I wanted the back stand to be super tight. You can play with the offset to lessen that. Feel free to tweak the design... I am still just learning to use Adobe Illustrator.
I also did a small rabbit on the bottom of the each shelf from where the shelf meets the stand to increase stability.
The holes in the shelves are for cable management.
This is a pretty straight forward design.... just cut, sand, fit into place and stop sitting at your desk.
Have fun!