Making Firberglass Parts

[UPLANDBOY]

HELLO ALL: I build scale models that have plastic parts such as cowls, steps, fairings and other pieces. The plastic is not durable and I would like to make them in fiberglass. I was thinking of coating the plastic part sheet with vaseline as a release agent and pushing it into wet plaster of paris. After the plaster dried I would remove the palstic sheet and use the plaster female mold to line with fiberglass and resin to make the parts. Your comments, suggestions, methods and recommendations are encouraged.
Thank you
Dave