This handy pack will make two trays that will work for tiered trays. Just add the post in between them! You get 4 8 inch sides, 4 12 inch sides, and 2 bottoms to fit them.
8″ x 8″ with 6 1/2″ x 6 1/2″ inside dimension
12″ x 12″ with 10 1/2″ x 10 1/2″ inside dimension
1/4″ thick backer in birch (not our normal birch)
Available only with a mitered corner (photo may show a straight cut)