I use wine bottle corks as holders for painting figures. I put pins in the figure's feet and stick it into the cork.
As for recycling other items...
I use plastic takeout containers to store and organize items in my stash, like various supplies for scratchbuilding, and smaller kit parts, various figures, etc. I use the rectangular containers with clear lids. I put labels on the ends, so I can find things on the shelf.
I recycle paint jars, particularly Tamiya paint jars, to hold various fluids on the bench and in my travel kit.
Old steel wool scouring pads turn into homemade rust powder.
All kinds of little plastic bits become raw material for scratchbuilds. Plastic bottle or jug caps. Seals from orange juice cartons. Vents from coffee packages.
Foil from packaging, or candy, becomes flags for my toy soldiers, or reins or other straps, blankets, etc.
Old ball point pen cartridges get broken down for the tube, the nibs look like small rounds or warheads for my MaK builds, and after soaking in isopropyl to clean out the ink residue, I get a tinted wash. The pen bodies are good tube stock.
Plastic jars make good storage containers, too. I eat a lot of peanut butter, so I have a lot of those larger rounder jars for storing things.
The wire handles from the cardboard containers Chinese takeout places use is a good source of general wire for pinning and similar uses.
When I have a Guinness, it's in cans here, and after I pour my pint, I cut the can open to scrounge the nitrogen widget inside.
Old insulated wire, fuse wire, I think the Brits call it, is a good source of fine wire stock for scratchbuilding. And digital equipment is full of great little bits of all shapes and colors, that are good scratchbuilding stock. Just as earlier generations of electric appliances were (and still are). Old stereo speaker cabinets can be turned into display cases.
All kinds of stuff to use, is all around.