I've tried doing a couple test pieces and haven't found a method I've liked all that much, does anyone have an idea or tips on how to replicate a see through/clear dome illusion or look on a R2 miniature?

I don't know if you have access to a vaccu-form machine, but that'd be my suggestion. Research (YouTube) on how they work, so you don't show up completely clueless or empty handed.

If you don't know where to look, try your local community college or university, even some high schools. We used one in our product design classes once in a while. The art or engineering departments each might have one that they'll run for you. Probably for free too, after you've shown your painted minis off. If they can't help you, ask them to point you in the right direction.

Hope this helps.