Belt and bag help
So I am working on a Derek Stiles from Trauma Center cosplay. So I think I got the overall pattern planned out now, but I need some help and advice for making the belt and bag. I want to make sure the belt would fit and be adjustable, but not sure as I never made a belt like this before nor a bag like that. I made a thread awhile back for the main costume, but for the construction of the belt and bag, I think this would be more of a proper forum as they more accessories. Thanks!
Here are some references-
Of what the belt and bag looks like (sorry, there is no back view)