sebo

Use poster board from the local craft shop or the drug store.
Keep cutting and pasting (scotch taping) parts on to the basic shape and keep refitting until it is close.
when it is close, draw that pattern onto a new sheet of poster board.
cut that one out and trim or add to make it a good fit.
draw that pattern onto another piece of poster board
fit it to the wind screen....if it is a good fit, trace it onto the plastic windshield material.
this has worked for me on a half dozen planes.
Sometimes I draw that one onto a piece of "SEETEMP" and trial fit that piece of seetemp..
If it fits good, save it in case you ever have to replace the windshield. You will be ready....don't forget to label that piece of seetemp.