The material is .032" polycarbonate. The sheet was cut into an 8 by
20 inch rectangle and hot bent slightly more than 90 degrees about
9 inches from one end. The bend fits into the cleft of the fairing
cutout, with the long section curving up under the windshield.
The exact orientation of the guard is a compromise, the angles chosen provide a balance between fit, streamlining and lever clearance. The upper, inner corners of the guards were trimmed away to clear hydraulic reservoirs.
Right now the shields are secured with clear plastic package sealing tape. When applied carefully it's fairly unobtrusive and seems quite strong. The guards deform slightly at freeway speeds but do not flap.
As illustrated the guards are probably a bit large, but the upper part is useful to keep cold wind/rain off arms. Combined with Hot Grips they make for very good comfort.
Thicker material would probably work better, obviously a better mounting scheme would be nice. The tape was used as a temporary mount but seems to work surprisingly well and threatens to become permanent 8-(.
Best of all would be to integrate the handguards with the windscreen.
[note added in postscript, 12/03] There seems to be nothing wrong with the material thickness; it's strong enough to hold shape at freeway speeds and soft enough to yield without damage in very tight parking. I don't much care for the tape mounting, but it works for six months before replacement.
The windguards are effective enough to make me favor the vfr in cold or wet weather, even when a lighter, more nimble bike makes sense.