How did you construct it?

Carla asked: [in reference to how the supports were attached]  What type of joints on the wooden cross support (did you use nails, screws or brackets)?

The cross members were fitted into notches in the vertical supports. See page 13ish (could change if I add more information) to see how the notches were cut. Here's a close up of the notch:

Separate screws are holding the 3/4" plywood in place than the support beams.

And in general, though the plans themselves detail this, the primary construction materials are as follows:

Pine 2x4's
3/4" C/D plywood
2 1/2" and 1 5/8" wood deck screws
pine 1x2s solely for shelf furring and stops