So far I've built one and I have 7 more to go, the good news is they go together quite easily however the first one took a while due to the vague instructions. Nevertheless it went together very well.
The plan is to film a 2 part video on building and painting the models as well as methods for installing couplers and adding weight to the car to bring it up to NMRA standards.
Filming of the video will start in the next couple of days and depending on the weather (The shed gets very cold!) part one should be finished in just over a week from now.
I'll post some updates here and I'll also post a written tutorial for this build detailing all the tools and materials so should you wish to build the same Hoppers as me you'll have all the information you need.
So stay tuned for the first video :)