Here is the knee armor pep file that I designed up & used which were designed using WOF's templates that are much more accurate looking than Firefek's. It is a modified Firefek file to look more accurate. Here is the back armor & collar that I used. I agree with RKD as well Raf's templates are awesome. I hope this helps & if you have any questions please let me know. I made up my own pep files for the knee armor using Wizard of Flight templates. I also made my collar & back armor from pep which was a modify file. I did make some mods to it to help in some areas. There are some inaccuracies about it but it does look decent. I went with the one that 'Skip' did that was base of Wizard of Flights templates. The helmet there are a number of these out there.
I would recommend a sintra for the armor. The only problem I see with using the trash can armor is paint adhering to it long term because of the type of plastic. They are also base of Wizard of Flight templates. These are also the ones that I used to make mine gauntlets & was done by 'Skip' as well. It is based off of Wizard of Flight templates. This is the one that I used to make my pack & was done by 'Skip'.