Well from what I can see in the pictures, it looks like they have some sort of internal support (especially the quivers and boots, else they'd collapse on themselves), very likely acrylic since that's fairly easy to get cut/shaped and is pretty inert. I see on the quivers there's a hook at the top, and I imagine that the internal support is simply hooked onto it. I see on at least one picture there's support on the bottom of the artifacts, not sure I like how much they stand out (I probably would have tried covering them with fabric close in color, or painting them).
The alternative to all the hooks and things would have been to glue them down (not archival and a big no-no in framing) or to sew them down, which again is frowned upon if you're punching new holes into the material. If they were simply sewn down they wouldn't have the volume that they show in those pictures though.
As for the background, it's a bit strong but at least it's a contrasting color and they may have had a reason for going with it that's not readily apparent to me.
I frame stuff for a living, can you tell?
