Dude, make a longboard. Like, from the ground up. I'm talking designing your own trucks, deck, and so on. It'd be a fun build, and would also be very fun to ride. The trucks would need tight tolerances if you build precision ones (trucks with a spherical bearing), so that would satisfy one of your requirements...

Here's a picture of an aluminum longboard that's already on the market:



Also, feel free to PM me if you have any questions about what goes into one of those boards, as I make similar ones as a hobby/ side job.