[JesseK]

If the mechanism is assembled together, the bolts that hold it together are included in the weight. The bolts move from the definition of COTS to being included in the definition of FABRICATED ITEM since they are in an assembled state. The same thing goes with motors, pneumatic cyllinders, servos, etc. Keep that in mind if you're close on weight.

There was a Q&A on this in 2012 I think.