I took off about 5-6 Lbs worth of Bondo and 4 paint jobs off the two aluminum doors that I have been working on. One doors shell alone was 22 Lbs before stripping and ended up being 19 Lbs naked.
I couldn't believe why someone would not strip off a previous paint job no matter how beautiful it was to apply a new one over it with a little sanding.
The top clear urethane coat alone must have been a pound or so on each door.
So you see, even a factory light weight part can bear unnecessary weight from years of use and refurbishment.
On my car, everything gets stripped down to its birthday suit and then a thin coat of epoxy primer/sealer or build up primer before the paint.