Determine the size you'd like your chalkboard to be and where you'll put it. A small chalkboard can be propped up with an easel and moved around. A wall-mounted chalkboard can be much larger.
Choose your lumber. Plywood comes in 8-by-4 foot sheets, different thicknesses and different quality grades. Look for a grade of wood called "project-ready"--this is pine board that comes sanded and ready to paint. Other types of plywood may be too rough to make into a chalkboard.
Purchase trim or molding for the outside edges of the chalkboard for a professional look.
Saw your wood down to size. If you do not have a good saw for this project, ask customer service at your hardware or home improvement store to cut it for you; many stores provide this service free of charge.
Prime the wood using a small bristle or foam brush. Allow to dry. Lightly sand the primer with fine-grit sand paper to smooth out the surface and wipe off dust with a dry rag.
Paint the primed plywood with chalkboard paint. Paint the trim with normal paint in any color you like. Allow everything to dry and apply a second coat if needed. Check your paint can for drying times.
Attach the trim to the chalkboard with wood glue. Secure in place with wood screws or finishing nails.
Allow to dry fully. Check the can of chalkboard paint for any special instructions before use--some brands require that you rub the chalkboard completely with chalk, then erase it as a kind of preparation.