HERE'S HOW TO MAKE YOUR OWN WHITEBOARDS!
The large whiteboards we use are 24" x 32" and they are cut from a 4' x 8' sheet of white economy tile board. Home Depot and Lowe's sell these sheets, and they will also cut them for you at a cost. We also drill a 1 1/2" hole in the top to use as a handle, and cut the corners of each board to get rid of the sharp corners.
Directions courtesy of Dr. David Henry