I've got a couple of Raspberry Pi Zero's that emulate a mass storage device (basically it acts like a USB drive) that I have connected to 3D printers and my wife's embroidery machine.

Instead of using it with a network share like in the link, I share the folder with SyncThing.

It's super convenient to not have to move a USB drive around and can just leave it connected and get the files on there seamlessly.