Made a number of lexan windshields from scratch (flat stock) for my 2001 Concours. The stock Concours windshield was an abomination with a flip at the top that only aggravated the turbulence. With no adjustable shield it was important to have multiple shields as the weather changed.
I found that a variable speed saber saw with variable orbital cutting action was the real key to clean, melt free cutting of polycarbonate. I would then use a small block plane with the blade just very barely exposed to shape the plastic to exact dimensions. The advantage to the plane was that, (on all but convex curves, of which the FJR shield has none), you get perfectly smooth radiused edges with no sanding required. Hand sanding will work but you have to be careful not to scratch the flat surfaces of the shield.
Some guys will flame buff the edges with a propane torch. That takes some real artistry that I don't possess.
Connie w/ shorty summer shield (was my favorite)
edit - yeah I've got a thing for BBB bikes.
Big Winter shield (I could almost get completely behind it, just peering over the top)
Cut some groovy '60's style
NACA ducts for back-pressure relief on the big shield.
The little aluminum scoop shape duct boxes that I attached behind the duct holess were not installed yet in the below picture.