Soldering iron : used to melt plastic to apropriate shape
Drill bits: useful when broken to use as keystock
Steel pipe: useful for breaking drillbits for keystock
50 ton press: useful for exploding bearings
Engineers: very useful for working knoledge of physics, cad and ROBOTS Also useful for not accounting for bolt space.
Safet glasses: Very useful for protecting you whole body, with safety glasses you WILL not get hurt
EVER 
Mouths: useful for holding onto and cleaning keystock, masterlinks and fasteners
impact gun: good for crossthreading holes
bottle caps: make good cirvo mounts
ipone oil: cutting oil and tap lube