I built this costume for my girl (dressed as Ripley) to wear at our Halloween party. I used a 1/12 model kit to get dimensions and used a ton of reference photos I found on the web. Between the fact that she's 5-1 and that I wanted her to get under our 8' ceilings I scaled the loader down to about 80% actual size - with a few adjustments here and there. Everything was built completely from scratch except the beacon light on top and the 4-point racing harness. Total time spent building: about 180 hours over the course of 10 weeks.
I am missing photos for a few steps (like the wiring) but the comments I received on my Slideshow convinced me this should still be a full instructable.
To see a clip of the loader in action:
UPDATE: G4's Attack of the Show gave a nice little shout out to the costume and the instructable! (jump to 1:20)
Step 1: The Foot
A 1x6 piece was attached on top of the foot and the lower foot is shaped with 1/2" foam insulation and 1/8" Lauan . The lauan paneling is light, and pretty cheap, and it adds a lot of rigidity to the foam. All the foam was cut with a hot wire tool I got from a craft store and then sanded smooth.