I have been looking around at various heat guns and I came
across Plastic Welding Rods Ldpe and Hdpe and Pvc.

http://tinyurl.com/grqkm

This is a world I'm not at all familiar with. What sort of
applications are these used for?

Also has anyone a view on the Steinel hot air guns?
I have not heard of them before...

Thanks,
Roy