: As i have deemed my 2x4 too warped to use i was looking for some advice on
: building one out of plywood. i would like to know if it is a requirement
: to use a router on the edges to allow them to fit together??

I recommend using a decent grade of cabinet type birch ply for this. A nominal 3/4" 4x8 was about $30-40 at the big box joints last I checked.

You want to build a stable structure, so it does help to rabbet in the top to the sides. A router is not needed - a table saw works fine.

Cut the sides to a full 4" tall or to whatever space you want to have in your forms. You can then set the blade and fence to take out 1/4"x3/4" notches in a couple of cuts on the back of the side pieces to accept the top and bottom slices. Use drywall screws and glue to hold it all together.

I made mine in two pieces with an oak joiner piece in the center so that I can break it down for storage. Just make sure you cut carefully to get dead consistent widths on all the side and top pieces.