Aluminum extrusions, rolling casters, a pair of handles and transparent tippable storage boxes in whatever sizes you need. This is an object few people see outside of a manufacturing or assembly facility, but I'd really like to have one of these in my shop or house:
That's Auer Packaging's sexily named System Trolley for Tipping Boxes, and it's a nice piece of modular design that makes good use of aluminum extrusions. There's no detail shots, but it appears each row of boxes is a single unit, and they presumably have protrusions that slot into the aluminum uprights.
The rows can be mix-and-matched, size-wise...
...or ordered in uniform sizes:
"The system trolley for tipping boxes from AUER Packaging ensures a maximum overview and individual access at all times thanks to the tiltable and transparent containers. Different tilt box modules can be combined as required. When ordering, you can choose whether the system trolley should be equipped on one or both sides."
These run from €274 (USD $313) for just the frame and casters, up to €505 (USD $578) for the unit with the largest boxes on both sides.