Bring on the resin casting!
I went out today and picked up the supplies that I'll need to do my plastic resin casts for my Ad Astra costume. The guy at the store probably thought I was a whacko, but was very helpful all the same and very diagnostic about my needs. Nice to know that the staff are competent so if I ever need help I can phone them.
I read through Amethyst Angel's tutorial and it all seems fairly straight-forward. The guy at the store gave me a clear walk-through on how to make my molds so I should be ok. I'm going to sculpt a positive tonight so I can experiment.