Excellent! Good luck with 'em, the pillars can be pretty easy to build as long as you don't get all ridiculous with them like I did by putting lights and sound inside them. If you're building them without sound/light, I'd just build the wood frame and cover it with foam directly as opposed to covering it with plywood and then covering that with foam. Your back will appreciate the weight difference.
If I'm not mistaken, that pic is from Haunt31? I believe he has it so his sign slides down to reveal something inside. Pretty cool idea.
Are you going to make the sign overhead as well?