Arnav, I thought you have way too much fun with the 1.5 buck huck and forgot about GWS!
Make a mold out of a cowl is very easy but not cheap. I poured molds for F4U and Zero, bought a heat gun from Harbor Fright (Hair dryer is not hot enough) and then made a cowl for Zero out of a 2 liter Coke bottle, which is 4x stronger than a GWS cowl. The total costs were around $20. I would say making a fiberglass cowl is doable but not necessary. Anyway, I have ordered the some cowls from Phill's hobby shop on eBay for around $2.5 a piece, glassed inside the cowl with 1/4 oz fiberglass cloth which also holds up well.