Hey!
How often have you messed up a single piece Aircraft Canopy? A few times right? If you haven't then you don't build a lot. Here's a very Finicky but useful way to make a new one if you cannot Smash mold or Vacuform and the Budget doesn't allow for Aftermarket Parts!
Get some very clear Sprue from Some friends who build Monogram kits. I know there are others. BUT, the Monogam material seems to come out Optically clearer as Sproo-Gloo. Now starting with a VIRGIN!! Quarter Bottle of Tamiya green Top, start making your Sproo-Gloo, You want it to be a little thicker than Cool Honey.
Now, take the original canopy and make a box out of LEGO, Megablox or whatever. I Even use small cardboard boxes. Take some Pla-Do and blend it till it's very soft and pliable. Put it in the Box and carefully push the canopy in it, being very careful not to distort it.
Very Carefully, pull out the canopy leaving that imprint behind. Put in Refrigerator for an hour! Put it in a Ziploc bag to keep dust away! Now being patient let the Pla-Do harden in the room air till it's a hard as a rock. BUT keep that imprint covered.
Now, Your Clear Sproo-Gloo should be ready. Before pouring you must do this. Carefully coat the Pla-Do with either PAM or Olive oil. Make sure it's NOT Runny! Very carefully pour the Sproo-Gloo into the pattern Cavity. the same rule applies here. make sure it's not too runny
You must be patient and keep rotating the mold till the Gloo sets up. Then Set it aside AFTER pouring Ice water in the mold. This will quicken the surface hardening. 24 hours later,take the mold and carefully saw almost to the canopy in four directions. The Pla-Do should then break off, giving you a nice clear canopy!
Let it sit for another day before trying to work with it. Yes, there's a lot of steps here. BUT, when you run out of options what do you do? Try something outrageous! It Works!