The materials required to build a six bin oast are:
4' x 8' x 3/4" sheet of sanded plywood
2" x 4" x 8' stud
Enough screen or metal lathe for (6) 2' x 2' squares
A box of screws (1"-1.5")
A few longer galvanized nails
Step 1: Ripping the plywood
After ripping the planks, cut them into 24" segments. Keep the set that came from each plank together so you don't need to worry about slight differences in the width between planks when framing the trays.