Our appleboxes are 12" x 20" x 1"/2"/4"/8" using 3/4" stock on the ends (many others use 1/2" stock on the handled ends) and center cripple, 1/2" material on the sides and tops / bottoms. 1x5" slots on either end on the full and half, 7/8" holes on the quarter and 1x5" slot at one end of the pancake. Note that our pancakes are not laminated 1/2" plywood - they are of true 1" stock.
We put ours together with Tite-Bond adhesives, brads and narrow-crown fasteners on the 3/4" sides for extra purchase. Routing, filling, sanding, stain and two coats of poly finish them out.
Ours are (each + S/H):
$28 Full (ACX or better)
$26 Half (ACX or better)
$24 Quarter (ACX or better)
$20 Pancake (Shop Birch / Maple)
$24 Mini Hi-Hat Board 16x16x3/4" (Shop Birch / Maple)
$30 Hollywood Hi-Hat Board 18x18x3/4" (Shop Birch / Maple)