craftgrrl | Mr Freeze's bubble helmet

This is gonna be text only but I have some pictures coming of other stuff real soon i promise!

I'm actually asking on behalf of my hubby. He's trying to make himself a Mr Freeze action figure. For reference for those who may not know who he is (I sure didn't until I married him but apparently knowing every single superhero in existence along with their villans etc is common knowledge and I'm just sheltered:P) This is what he's going for:

He's got pretty much all the components figured out except the bubble over his head. So I'm scouting for ideas for how we could make this??? We've tried a few different things - the closest to success was warping a plastic drink bottle over the top of a testube with a heat gun but it wouldn't melt smoothly. I went to the candy machines around town looking for those little plastic toys that used to come in those cases thinking we could use one of those but there aren't any that have them anymore.

We have access to a large amount of tools and mold making materials and we have plastic we can cast in but its not clear and we can't afford to buy the clear stuff right now.

anyway i realize it's an odd sort of question but any ideas or suggestions that pop into your heads would be really welcome.

x-posted in my own lj.