Just another caution beside the measurements: the FCG needs to be level and the arms need to be securely tightened. I hooked this up to a timer to run 3-4 hours at night the week before Halloween. One of the arms worked loose and was pulled toward the motor. This fouled the line jamming the rig. When I checked it the next day the motor was not working so I unplugged it and went off to work.
After simultaneously cursing and crying, I contacted MonsterGuts about getting a replacement shipped out, which they would do their best so I could get it before H-day (yet another example of great customer service). When I got off work, for some reason, I tried the motor again and Thank the Halloween Spirits it worked, so I cancelled the replacement. Those FCG motors are tough little buggers. To prevent this from happening again, I added a cross brace using flat aluminum stock that would prevent the arm from moving. Cheap and fast fix. The prop performed above and beyond the call of duty the rest of the week. It didn't even need the gate I planned for...well maybe some day!
The only thing I'm considering doing to it is attaching wood strips (aluminum stock if I can afford it would be just as good) to the wallboard to stabilize it. The wallboard is hard to handle by one person and is awfully floppy.
Well that it. Hope the pictures give you a better idea on the construction. I plan on getting a number of years out of this prop.
2010 update:
The walls survived the year but I don't think that it is a long-term option. I plan on replacing them with cheap thin paneling but keeping the brick scene-setter covering. Hooks that can fit the PVC frame will help in hanging the sides.