I've been making bracket prototypes for Plugable over the summer and this design is specifically for the 7 port USB3 81x model hub.
The purpose of the design is to allow several USB hub to be stacked together and then secured to the top or underside of a desk. It declutters the space and allows easy accessibility for your USB devices
By breaking the bracket into multiple, small components, the user can print out exactly what they need for their unique workstation arrangement. It's also great because each piece is quite small and can be done on even on printers with smaller print beds.
Here's a blogpsot detailing a bit more about the design:
Printed at 20% infill.
-Use a pair of Base Brackets to secure the hub on either side.
-Insert pins and then stack Middle Brackets as needed.
-After final bracket is added, insert pins and add Top to secure the whole thing.