This is a walking model of an AT-AT from the Star Wars films. It is powered by a 9V battery and a 90 rpm motor. Everything else is 3d printed using roughly 750 grams of filament.

Here is a short video of it walking

User Morbihan has done a remarkable job at redesigning a lot of the parts to work better and print better and I highly suggest you check that out. http://www.thingiverse.com/thing:2043900

Also, thanks to user dobrink for printing a much cleaner model and sharing a video!

The entire design includes of 69 individual parts (28 STL files). It sounds like a ton but most of them are small easy prints. I printed a complete set of parts in about four days. Depending on how good your printer is it may take some hours to clean up the parts and assemble it. This is a large model, it's almost a foot tall. Make sure your printer is large enough to print all the parts as they cannot be scaled down!

The non 3d printed components can be purchased here:
Motor - $13
Switch - $0.75
9V Battery Clip - $1.25
(I used a battery clip I had laying around so you may need to cut and solder the wires)
You will also need some super glue.

As always, if you have any questions feel free to send me a message.