That will certainly get you a close up pad on a hard back.
Personally, if I'm going to the effort of carrying around a nice hard backed close up pad, I would want something that looks much nicer than that. No exposed foam, for example, and something sturdier than the felt that's usually on the average close up pad for the top surface.
One suggestion with what Maaz said - don't clamp right onto the pad itself, unless you want dents. You'll want to put another board on top to distribute the force of the clamps around the whole surface evenly, and even then you may end up compressing the foam a bit. Running a brush (like a boars hair brush - obviously make sure it's clean first) will restore some of that felty texture.
If I were to make one myself I would use suede for the top surface, or maybe certain types of microfiber. One layer of hard wood, with the leather/suede/cloth wrapped around that from the bottom up, then take a thin stiff board, put foam on top of that, and wrap all that with suede/leather/cloth from the top down. Apply an even coat of adhesive, clamp it all between two boards, allow 24-48 hours to cure, depending on the adhesive used.
Like I said in my previous post - cheap, or good - pick one. You're either paying with your own time and energy to get it right and looking good, or you're paying money to someone else who will do it for you.