I haven't bent any coroplast with a heat gun but i'm guessing you'll only want to heat the inside of the bend. The skin of it is so thin that if the outside was heated it might stretch and deform and end up a mess. Also, the internal ribs will complicate matters by running along a different line than the bend you want. Murphys Law remember?? lol!
So i'm guessing you'll want to make a series of little bends close together so you end up with one big bend.
As i say, i havent done this but i have experience working with materials so it's an educated guess, subject to correction of course.
I have a few sheets of coroplast lying in my shed. I just need to find the time to use it! I also got some foam pvc sheet for my future kammback and wheel skirts:
Foam PVC Sheet - 365 Plastics - Access Plastics Limited
I used some to blank off my fog light blank inserts and it bent well over the gas hob. Held its bend too. Plus it looks almost stock, apart from the screws.....
I figured it would look better than coroplast and would form better too. It was 20 euro for an 8'x4' sheet. Again, between working nights and looking after the kids, i don't get much ecomodding time.......
Unlike you, Adam. You're powering through this ecomodding at some rate!
Best of luck,
ollie
Having said all that i'd try bending the coroplast instead of joining. It's going to be harder to get the join to look respectable, what with brackets, screws and the edge itself. Plus, the bent coroplast will be more rigid and a little lighter without the brackets of joined coroplast.