The Mantis Walker is a two servo walking robot. I've included the build instructions as a PDF.
It uses an ultrasonic sensor to detect and avoid obstacles in it's path as shown in this video:
Print out the body, the battery holder and the legs and follow the instructions to build.
I have included the Arduino sketch and the wiring diagram for the electronics is in the PDF.
All the electronics I got from ebay for about AUD$13.
The total list of parts I used:
Printed Mantis Body, Battery Holder and Legs
8 x 4G 6mm machine screws
2 x Tower 9G micro servos (which come with servo horns and screws)
1 x Ultrasonic Range Finder
Jumper Cables - male to male
1 x 9v Battery
1 x 9v Battery clip
1 x piece of Perfboard
1 x Arduino Nano
Female header pins or Nano socket
Male Header pins (need 3 + 3 + 4)
1 x PCB switch (optional)
1 x PCB battery header male and female
Hook up (pref. single core) wire