Earlier, John Galloway wrote:

...made from proper mecaplex...

Just to be clear about such things, Mecaplex is the company in
Switzerland that makes canopy transparencies for many European and
other glider companies:

http://www.mecaplex.ch

Acrylic (such as Rohn and Haas Plexiglas(tm)), and less often
polycarbonate (such as DuPont Lexan(tm)) are what they make the canopy
transparencies out of.

Mecaplex also makes most of the sliding windows and rails used in
glider canopies. For these products, they usually use a standard
acrylic casting with "Mecaplex" embossed on it.

Contrary to popular belief, Mecaplex canopies are quite cost-effective
when ordered in moderate quantities such as a box of ten. They only get
expensive when the sailplane manufacturer adds their markup, and then
the distributor adds their markup plus intercontinental freight, and
then the installer adds their fees plus local shipping charges. Then a
$700 bubble becomes a $3200 proposition.

One place that seems to specialize in UV-blocking acrylic canopy
transparencies is Thermotec:

http://home.inreach.com/thermotc/

Be prepared to supply your own tooling, or pay their rates for
developing tooling to make one-off articles.

Thanks, and best regards to all

Bob K.
http://www.hpaircraft.com