I build my own equipment and sell hives also.
I use 3/4 inch thick lumber.
But be careful not all lumber is planned alike, some is 3/4 inch thick and some is 13/16 inches.
If using box joints use a caliper to get the correct thickness or the joints won't be the same lengths.
When making boxes cut all long boards 19 7/8 inch when using box joints and for 10 frame equipment 16 1/4 inches long for the short boards or for 8 frame make them 13 3/4 long.
Then depending on the type box, Deep, Medium or Shallow, 9 5/8, 6 5/8 or 5 11/16 inches
If cutting boards for Rabbit Joints make the long boards 19 1/8 inches long by however wide you want the box deep.
The short board will be the width of the box 16 1/4, 13 3/4 and so on inches wide.
On each end of the short boards cut a rabbit joint 3/4 inches wide and 3/8 inches deep or half the thickness of the board.
That will give you a box exactly 19 7/8 inches long by however wide you want, 10 or 8 frame box.
To make a 6 frame box cut the short board 11 1/2 inches long and a 5 frame box 9 1/4 inches long.
Cut a 45 degree angle on one end of each board.
Using a Dado Blade cut a 3/4 x 3/4 inch rabbit joint the length of each board on the inside top.
That gives you a perfect space to staple your #8 wire in.
The butt end of each 2x4 cut a 3/4 rabbit joint from the top of the 2x4 to the bottom.
The back board is 14 7/8 inches long.
at the top cut a 3/4 rabbit joint facing the inside of the frame.
The front board is 13 1/4 inches long, rip 3/4 inch from the 2x4 to match the rabbit joints on the side boards.
Place it at the peak of the 45 degree angle cut on the side boards.
Now cut a 1/2 inch rabbit joint on the side boards and front boards 1 inch off the bottom of the board.
Now measure and rip the back board to match the 1/2 inch rabbit joints. this will make the back board 2 pieces.
That way you can slip a board in during the winter to cut down on cold drafts on the bees.
Now take a 1 inch board 4 1/2 inches wide by 16 1/4 inches long and cut each side 45 degrees the same direction.
This is the landing board.
Glue and nail all pieces and you have a very sturdy screened bottom board.
For 8 frame make the rear board 12 5/8 inches long and the front board 11 inches long.
The landing board will be 14 inches long.