I know this is an old discussion but I was just looking into this and happened to stumble on it. I also stumbled on an answer, for what your wife is looking to use them for she can probably skip the resin step entirely and just laminate them. Like straight up school days laminating machine style. This just came out not long ago. I have not tried it yet so I hope it works (for both of us) and that this is not too late to be of any help!
http://www.resinobsession.com/resin-tutorials/casting-butterfly-wings-resin
