The RepWalker is a Shellmo module. Shellmo is an open source robot project with it's homepage at shellmo.org and a forum at shellmo.net. A Shellmo should have legs, a heart and eyes - you can find the eyes for my Mutant RA04 here http://www.thingiverse.com/thing:328939
I have designed this RepWalker Mutant RA04 based on Sho's original RepWalker. While he wanted a light weight robot to print on Shapeways (each sq cm is money) I redesigned all parts for my RepRap printer. This means material doesn't matter, no fine details and the focus on "easy to print" and robust to play with.
I also looked for easy to source muscles and designed RepWalker Mutant RA04 to be powered by hacked standard servos with a 40 x 20 mm (about 5 US$ at HK - I used this one with two ball bearings plus one brass bushing in the gear train for added smoothness and precision http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=44049). You can find some info on how to hack such servos in the net or on my web page (such continuouse rotating servos can also be sourced already hacked...)
The RepWalker is a platform for an Arduino based robot. You can pimp it with bumper switches and all kind of sensors. You can design your own building platform on top of the #18-collarbones or just place the Arduino on the #20-brain-fastener. Be creative and enjoy this little robot platform.
We will publish more add-on's during the next time. So please have a look at shellmo.net to see what is going on and to share your creations!
http://youtu.be/Vk3opU5dge8
You will find a detailed assembly instruction on my personal web page at: http://shellmo.radow.org/repwalker-ra04/repwalker-ra04.php

The design hight of all parts is 0.5 mm. Because of this you should print it with a layer height of 0.5 mm (with your RepRap 0.5 mm nozzle) with 0.25 mm layer height (on your MakerBot) or with 0.125 mm if you have too much time...
If you have a not so good calibrated RepRap you should print the parts #1, #4, and #5 in the given orientation. This ensures that you can assemble it even with a miss calibration.
For one RepWalker Mutant RA04 you will need the following parts:
1x #01-muscle-torso
1x #02-spine-left
1x #03-spine-right
1x #04-hip
1x #05-shoulder
2x #06-hip-joint
2x #07-shoulder-joint
2x #08-ankle
1x #10 hind-leg-right
1x #11-hind-leg-left
2x #12-foreleg-right
2x #13-foreleg-left
6x #14-tendon
12x #15-meniscus (print some more)
You will find some tray combinations in the thing files as suggestion.
If you like to pimp the RepWalker you can print also
1x #16-forehead
1x #17-buttocks
2x #18-collarbone
1x #20-brain-fastener
The RepWalker can stand on his feet only with assembled servos. You can print my servo dummy's to do so. Search for "Standard Servo Dummy 40 x 20 mm base" here in Thingiverse.
All parts are assembled with M3 screws and nuts. 10 mm in length for the chassis 12 or 16 mm to mount the servo.
The #8-ankle will be glued to the servo disk .You can do this for your tests with double sided tape. Afterwards I suggest Epoxy glue or something like that.
You will find a detailed assembly instruction on my personal web page at: http://shellmo.radow.org/repwalker-ra04/repwalker-ra04.php