Vinamold is the stuff i was on about. You could do as Stevo_com says above, but make a cast from vinamold. as its flexible, its easier to get it off the original positive (whatever that may be). Then when you cast the resin, you can just cut the vinamold away.
It's actually slightly addictive once you've had a go. I went on a casting spree, not helped by the fact that i was doing an art degree at the time: The most esoteric thing i made was a clear resin ice lolly filled with dead wasps... #bloodystudents
Vinamold is the stuff i was on about. You could do as Stevo_com says above, but make a cast from vinamold. as its flexible, its easier to get it off the original positive (whatever that may be). Then when you cast the resin, you can just cut the vinamold away.
It's actually slightly addictive once you've had a go. I went on a casting spree, not helped by the fact that i was doing an art degree at the time: The most esoteric thing i made was a clear resin ice lolly filled with dead wasps... #bloodystudents