While I could have just left them clear without any effects except basing (as I've done in the past), I wanted to try and make these look unusual, so mimicked the look of their illustrations. While I'd originally planned on doing this with an airbrush, my skills just weren't really up to the task, I thought, so, I went with paint.
Said mini-tutorialFirst, on assembling plastic, your assembly options are largely limited since regular plastic glues don't work, and super glue can leave a residue. Furthermore, you can't use greenstuff or filler to patch seams.
What I've done with these is use super glue first, then I've very heavily layered undiluted gloss varnish, which, over the course of several layers, will eventually smooth out the surface. It's worth noting that you'll need to be ready with a fine instrument (a new hobby knife or a pin, for instance) to pop bubbles as you put the varnish down, if you don't want them showing up in the dried layer.
Painting on clear plastic, if you do it wrong, you're stuck with something overly opaque or with your paint beading up.
The first option: if you don't care about a glossy finish, hitting them with a matte varnish (or even a glossy one) will give your minis enough tooth to paint on, like primer, which will prevent beading though still may be too opaque.
The second option: use paint retarder: it's a way of changing opacity without dramatically effecting viscosity, so it will still go on like thin paint (if you don't go overboard), and you can effectively put down glazes or paint like normal.
The third option: airbrush them. This will still require sealing, though, while the middle option won't, if you're careful enough with your models, particularly if you either leave the base edges raw plastic or seal them before attaching them, since both
Back to these minisFor these, I focused on glazes and, after testing the effects of matte varnish and then gloss varnish on the transparent parts, decided that I wasn't sacrificing much by protecting the minis. However, I found that they actually caught the light better and, in my opinion, fit the look of everything else I've done better, when they were just matte varnished with a bit of the glossy plastic below giving a bit of shine.
The top set is under normal light, while the bottom set is hit from behind with an LED light.