[ent]

There's at least this: https://hackaday.io/project/167446-diy-inkjet-printer

But as others have mentioned, commercial printers are really cheap, especially for how complicated they are to replicate so there's not much motivation to make them.

[Fnoord]

The printers are cheap (if you also need a scanner price is going up a little). The ink isn't cheap though, its artificially high, and all the major printer manufacturers actively hamper your ability to go for a non-branded ink version. Cause that is where their profit margins lie.