I made a similar one, with a couple variations if ya don't mind...
For the main axle, I used a piece of SS rod, ends drilled for Cotter pins to hold the wheels on, inserted into the PVC, easy to change wheels and breakdown if needed.
The 'rack pads', support frames weren't glued so you can rotate them for a more flat storage, and reduced the height of the PVC from the axle T to the rack pad T lower, only used enough PVC to connect one T to the other. Less chance of PVC flex and keeps the center of balance lower.
Clean setup though and way to just give it away...
