Before I had my van I'd always end up filling my pack with way too many crafting supplies. Typically wiring wrapping and sewing supplies; pliers, wire cutters, various types of wire, scrap fabric, hemp cord, fastners, buttons, zippers, and a bajillion little stones and trinkets for making stuff.
Now that I have a place to store everything I also have; polymer clay, spray paints, acrylic paints, fabric paints, tons of leather, straps, clasps, velcro, matte and gloss finish, leather hole punches of varying sizes, rivets, belts, and probably a whole bunch of stuff that I'm forgetting.
I like to blend all my mediums together too though typically I make stuff that is to be worn. Like jewelry, pouches, that sort of stuff. I like having everything on hand for when I have a project in mind.