Construction details:
1.
Set two boards aside for now (coded yellow and green below).
2. Take the third board and cut it into four 12" x 12" pieces.
3. Cut 4 in. off each of the 12" x 12" pieces, and you will have
- four 8" x 12" pieces (the blue ones below)
- four 4" x 12" pieces (the red ones below)
4.
Now glue the 4" x 12" (red pieces) to the bottom shelf (green). I spaced them 24" apart (see diagram). Then nail them to the shelf with 1 " nails. Spacing can vary, but I chose the dimensions in the diagram to fit my equipment needs, and used only 3 of the 4 pieces. Use all 4 of you wish, depending on your needs.
5. Next, glue/nail the four 8" x 12" (blue pieces) to the bottom shelf (green). Spacing can vary, but I chose the dimensions in the diagram to fit my equipment needs.
6. Next, glue/nail the top shelf (yellow) to the 8" x 12" pieces..
7. Finally, you can stain and varnish the completed shelf if you wish to create more of a finished "wooden" look. I chose a walnut color to match my desk.

Overall Dimensions of the Shelf