Cheap Casting Material?

[thirtyacre86]

i am looking for a cheaper way to make casts of my fish rather than rtv silicone. i tried plaster of paris but my urethane plastic adheres to it thru its pours. i have yet to try my spray release agent thinking that it wouldnt help. is there a different release agent that would work better with plaster of paris, or what is another cheap material i can use to make my casts that urethane plastic wont stick to?

[CrabCrazy]

shellac your plaster molds...wax with any paste or car wax.....spray or brush PVA over wax...cast will not stick to plaster...a cheap way is to coat plaster mold with a water base gloss finish......then scrub in some vasoline.....blow over mold with hairdryer...this works too...i use it when casting parts like water lilys,parts of a fish for my crab mounts and rock molds

[J. Scanlan]

You can mold out of bondo/ resin mixture. Coat mold with Mothers wax and PVA. You can cast urethane productions with no problem.

[CrabCrazy]

for me plaster is cheaper,then bondo ..if you are making just one cast...if the plaster is mixed right, detail will be good...i first seal the fish with a light coat of clear lacquer first....for the first coat of plaster, I paint it on the fish...this breaks up the air bubbles and helps to pick up the detail better....just before it sets, i add wire or soft mesh and pour over a second coat...after the mold is dry, shellac the mold with thin coats, until the mold takes on a sheen....then wax and pva the mold and its ready to go...to remove the cast i break the plaster away to remove it...careful around the head area...once out, the detail around the head is better, because you broke away the plaster, so undercuts are not a problem...plaster is cheap...for $15 for 25.lb plaster...I can mold a lot of fish 7.lb or smaller....for big fish plaster is cheaper then bondo/glass mix IMO