Strider Ver 3's leg and crank instructions are here
Strider Ver 3's frame instructions are here. This frame works for both the Mindstorms and the battery box versions, and can use either 8 or 12 legs. If building a Mindstorms Strider, be sure to check out the instructions for mounting the brick higher here before starting your build.
Strider Ver 3
For better functionality for Mindstorms Strider Ver 3, see these instructions for mounting the EV3 brick higher
Mindstorms Strider with the Brick Mounted Higher
Simplified instructions for building Strider Ver 2's leg mechanism
Strider's Paired Leg Mechanism (ver 2)
Wired Strider Ver 2 Build Instructions and part list