Here are a few cool bike tools that you may not have heard of.
This is a wheel dish tool, its used to dial in the amount of center/off center from the hub the rim should be, factoring in the cassette width
This is a Tensiometer, its a calibrated tool for finding the KGF (Kilograms Force) of a tensioned wheel spoke. A properly tensioned and balanced spoke wheel is a force to be reckoned with.
I love building wheels, its so calming.