The idea is to make it looks like I'm sitting in a chair riding atop a steam-powered mech that walks on two robotic legs. In reality my seated legs are false, and my real legs power the robot's legs. This is basically a variant on the age-old circus-clown costume where someone looks like they're riding a horse, and is also inspired by Ben Hallert's APU costume and the paintball mech costume called Steel Dawn.
While not fast enough to keep up with 6-year-old trick-or-treaters as they went from house to house, I was still able to walk down the street and show off to passers by. The most common reaction was along the lines of "Wow! That's the coolest costume I've ever seen -- what the heck are you?!? I also got little kids (and some older kids, who really should know better) asking me how the thing was powered, several adults admitting they couldn't figure out how the thing worked, and at least one little girl bursting into tears as she saw me ambling towards her. All in all, I'd say it was a big success :).
Step 1: Build the frame
Next I built a box frame out of six lengths of Â½"-inner-diameter PVC pipe, two 'T' joints, two 90Â° elbow joints and four 3-way corner joints. Connected to the 'T' joints in back
are two short lengths of Â½" PVC, which fit inside the backpack-frame pipe. My first prototype was just as wide as the backpack frame itself, but that was a little too tight a squeeze so I widened the frame by adding a couple of 120Â° angle joints to each side. Once everything was tested I used PVC cement to secure all the joints, except for the front cross-pipe which I left free to turn. That pipe needed to remain free to turn so I could fold up the leg-holder for easy storage. I made the PVC box frame the right length for a chair such that my knee would
come to the far end (about 21" for my leg-length).
I then drilled a hole through each of the back PVC connectors to match the holes in the backpack frame, so when the backpack was connected to the PVC frame I could use the existing cotter pins to secure them to each other.