"SBH" wrote:
I am building a plyometric jumping box using 3/4 plywood with about a
7 degree taper (to avoid tip over) with a platform size of 20 x 24.
There will be 5 total boards; front, rear, right, left and a center
for extra strength. I am thinking about dadoing the corners and the
center on the front and rear boards for the sides to slide into to
gain extra strength and stability as opposed to just butting the ends
together with glue and nails.

If I were going to build these, I would use epoxy, fiberglass and
fairing putty made using epoxy and microballoons.

Position the pieces using butt joints that are "close" (they don't
have to be exact), then apply fairing putty.

Next day, sand off rough spots, then apply a layer of glass wet out
with epoxy.

Let it cure a couple of days before using.

The plywood will turn to compost before the joint fails.

Lew