My space also has slanted walls. For my stash storage, I took the triangular-shaped wall and hung curtains from it. I made them from inexpensive drop cloths that I bought at Harbor Freight, bought some clip-on rings and hung them from hooks on the wall. I put shelves behind the curtains and plastic bins to hold my fabrics. When I need to get my fabric, I just unhook the curtains and pull out a bin.
I'm sure you are done now and your place looks fabulous, but I would suggest that if you have the money, (or do a "free" search on CL,) you get some file cabinets to store the stuff that you have in the plastic drawers. I have a few of those drawers too and I find that they seem to attract dust, they're always falling apart and they feel so temporary. The cabinets will fit neatly under the slanted wall and look much nicer. They may even give you some desk top space to work on.