Reproducing BIG plastic pieces?

Okay... I'm pretty sure this is impossible, but it's worth a shot. Here's the deal. The big side pieces on my Virtual On cab were already in horrid shape and were cracked all over, but when I removed one side the change in pressure from removing the bolt split it at the top of the piece (not horribly noticeable, but it irks me) and the steel puddy I had used to repair spots before didn't harden the way it was supposed too and looks HORRID but is strong enough that I can't remove it without messing up the plastic worse. I have new sideart and stickers ready to apply to each side, but naturally I'm thinking that this may be beyond what I can make look decent regardless.

Here's my question--is there any method, or place, or person that can reproduce LARGE plastic pieces like this? (or anyone who happens to have these lying around, miraculously) I've wanted transparent (or at least translucent) plastic for these pieces for another cool thing I'm adding to my custom restore, but I've no clue how to go about doing something like this and all googling has got me is how/where to reproduce tiny car parts. For what it's worth, this is what I'm looking at reproducing (NOT MY PICTURE):


(this is the British cab so the bolt placement is a bit different but it's basically that)

ANY input would be appreciated. At this point I'm close to just smacking duct tape over the corners that are messed up and saying it's "industrial style".