I wonder why, with the ubiquity of DIY open source 3d printers, I can't seem to find a single open source design for a document printer that takes standard tone

I wonder why, with the ubiquity of DIY open source 3d printers, I can't seem to find a single open source design for a document printer that takes standard toner cartridges. Youd think something this simple would find the interest of some hobbyist out there.