TG, there's a couple factors at play here that have nothing to do with
how the tank/seat is molded. Whatever method you choose, the deal breaker will be body filler. First off, how perfect you can get your foam mold before laying the glass will substantially affect the end weight (and with CAD and a CNC, that's as good as it gets!). More low spots to fill = more filler. This can be remedied by building up the glass higher than the required thickness for the strength you need, then sanding down all high spots to match the lows, bringing you to your desired thickness, which will be the same regardless of your mold type. (I know you know this, but for the sake of all who read this...) It worked pretty well for me on the seat, where the outside layer was pure fiberglass.
It did not work well on the tank, where large sections of the outer layer were Kevlar. Kevlar can't be sanded down, so any low areas have to be built up. Add to that the fact that I had to coat the inside with a thick coat of fuel liner, and the end weight of the tank is right around that of the stock steel tank (maybe more!).
The seat on the other hand, is incredibly light. I don't have a scale that is accurate that low, but comparing it to dumbell weights, I would put it at 2 to 3 pounds. Maybe less.
The only problem with offering reproductions of my seat is that it is tailor-made to my frame, which is not at all stock in the rear!
And you're right about the mess from fiberglass and foam...it's ridiculous!
xsmooth, if you're female, send me your age and cup size.
