Thanks, guys! I don't have a how-to but it's just framed with 2x3s and skinned with luan and 1" thick extruded polyurethane foam (pink stuff) that was carved up and painted to look like stone. The screen is a cheap shower curtain stretched on a 1x2 frame. The garage door still closes behind it
I just uploaded a picture taken on the inside to this album to give you an idea how it goes together.