Under localhost:631/printers, the following appears after I create a printer, even a raw one, and even if I log in as root:

Printer State: stopped, accepting jobs.
"Unable to open USB device "usb:/dev/usb/lp0": No such device"
Device URI: usb:/dev/usb/lp0

However, /dev/usb/lp0 does indeed exist.

The printer is a Samsung SCX-4200, which works perfectly well as a copier. Could this be some sort of issue with modules, perhaps, or might I need to change a configuration file?

See www.linuxprinting.org if your printer is supported. Maybe it needs a special driver?

I have a ppd file from the manufacturer, however I recieve the same message whether I use the ppd or set up a raw printer.

I've looked at the manufacturer page. There is a driver there whith 14MB in size. So I conclude the PPD file is simply not enough. Download the driver if you haven't already done so and follow the instructions (note you need root privileges to run autorun). Then, if the programm doesn't do it itself, install your printer again, but do select your exact printer modell (should appear in the list), not RAW or something else. You won't need to specify a PPD file neither.

Note: by following Samsung's instruction, your unpacked files can not be deleted as user. Better run the "tar" command as normal user if you are working in your normal user's folder. Then get root privilege to run the programm and change file permissions if needed.

Thank you, but the "driver" is merely a collection of dozens of ppd files ( one for every printer Samsung makes ) with a few scripts and a graphical installer; that is where I got the ppd from.

The issue turned out to be not with software, but rather with my USB ports not being properly connected to the motherboard when I assembled the computer. Now printing works perfectly.