I've seen a few similar posts recently (not a bad thing to be aware). Epson, HP...
Is it possible to 3D print a printer that can be topped up with any old liquid / inkjet ink. That might be popular. Beside the obvious privacy protection, such a printer could be easily maintained as broken parts could be replaced easily enough.
Seems there's a gap in the infamous market.
I imagine one of the main problems is that the actual 'printer' end of such a machine will contain proprietary parts, possibly locked behind IP walls. So if these parts cannot be printed, they have to be bought, and big manufacturers can get their data by selling those parts.