I love this spider-like walking mechanism, spotted on the MAKE Flickr pool. Here are some of the deets:

The walking action uses the Klann linkage, specifically, configuration E006. The motors are Solarbotics GM17, from Technobots, which will generate a decent torque from 5v upwards, and a nice scurry at 12v. Pivot bolts are all M3x10 and x14 button head allens (MF-BH34S et al) & nylocs (MF-NN03S), from http://modelfixings.co.uk. Plus a 44mm bit of M3 studding. The gears are held onto the shafts with No.2 (2.2mm) by 6.4mm and 9.5mm self-tappers (MF-ST09). Motor mounts are M2.5×20. Gears are mod 1.5, 30mm pitch circle, 14.5 degree pressure angle. They’re designed with CamBam’s cog tool and cut from 6mm acetal sheet. Acetal is from http://www.directplasticsonline.co.uk/ The sheet thickness is a bit variable, so if you use our CamBam files make sure you adjust the cut depths for the sheet you have. This project was inspired by this cute little thing.