Hi Marc,.. yes you can make one from lexan,..without a pattern it takes a little more time,..but can be done . get some measurements off your present wndshield so you'll know what size piece of lexan to get,..you do have some choices on grade of lexan,..I'm using M-5 bronze on my doors and turtle deck,..and clear on the front. (M-10 requires heating to form)

1/8" clear lexan,..leave the protective skin on the lexan until you have finished cutting the new windshield.

your going to have to have the wings folded back to start with when sizing the new screen. once the old windscreen is removed,duplicate the bottom arc on the old screen to the new lexan where it meets the cowl,.cut that piece but add an inch or so it can be trimmed later if need be.take the new lexan and place it in an arc where it meets your top leading edge of instrument panel and cowl, use some squeeze clamps at the door posts to hold it ..put the top nose cowl section on and put a rolled towel on top of instrument panel pushing the lexan out to meet the top section of your cowl,. now pull the lexan to the top of the door post / front wing attach point and clamp it there too,,swing your wing towards the lexan and trace the leading edge where the wing meets the lexan,..do both sides,.. and trace a line down each door post on the inside of the door opening.
remove the lexan,..you'll need a drill ..a hole saw I'm thinking its a 2.5 Inch hole saw,..and some good tin shears,..the straight edges you can cut with the tin shears..the section where the wing meets the lexan you'll need to use the hole saw,..once you've cut to this point ..put the windscreen back on the plane in the same manner,..and this time swing your wings to flight position and put the pins in,..you might have to manipulate the lexan a little ,,and or trim a little but once it fits well around your leading edges and you have the towel back in pushing the lexan out to the cowl ..,..you can fold the top part of the lexan down on top of the wing,..grab a bag of dog food or something to hold it down on top of the wing..do not cut this section yet.
Now once all of the front section looks good you can start your drilling,..start at the top just under each wing and work your way down.and then cut the top to fit,..in place or mark it remove it again and cut it ..once the cutting is done remove the protactive covering from the inside edges and where your attaching the wind screen,..
the top ,..ensure that your lexan is flat where it meets attach points,..once you know that it is,..start at the leading edge and work to the rear on each side about 3 inches from leading edge ..then go across the back where it meets the turtle deck,..then come back and finish from where you stopped at the 3 inch mark on each side of the top,,

sand all the sharp edges with fine sand paper peel the rest of the protective skin off ..and try her out

hope this helps

Chase