MY hero!
Justin, you exemplify the true spirit of homebuilding!
most would just say, 'where can I buy this already made, today!?'
I think it would be a wonderful project to make your own tip lenses.
.....you may even be able to sell some to others, and that's quite rewarding, in a warm fuzzy kind of way, if not monetarily.
If you look at Van's tip lens blank, ( sort of a big lozenge shape) you can see how one might go about it.
after a few hundred hours of making forms, setting up ovens, and wasting a couple dozen sheets of plexi, you will probably come up with a nice lens.
( don't tell the missus what you're doing in her oven!)
keep up posted if you go this route.
here's a good start, some light reading:
http://www.plexiglas.com/export/sit...loads/sheet-docs/plexiglas-forming-manual.pdf
P.S. I have to caution you that a good friend was warming up his big oven to pull a canopy, went to town to get one more thing, and came back to find his garage, nearly complete wooden aircraft project, and camper he had just restored, burnt to the ground. Don't use plywood for the oven, use at least fire-rated drywall, or metal, and NEVER leave when it's on!