Hey Bonch,
I give credit to @WillAdams for the design. He posted a picture of his layout and I basically copied his and used my own numbers for the width of the slats. Below is a section from an earlier post I made. http://community.carbide3d.com/t/waste-board-finished-at-last/4420
Hope this helps.
With a special thanks to @WillAdams’ post showing his layout plan, I set to putting mine in order. I believe he used a PVC material. I opted to cut 1-1/2, 3, 4 & 6" slats of 3/4" MDF. I don’t know the exact dimensions of Williams, but mine must be fairly close.
The MDF slats and T-tracs are screwed directly to the original waste board.
Thanks,
Bill