People have attached pens to 3d printers and used them to write letters, effectively print. Most consumer 3D printers are useing or based on open source software.

I think the issue is, printers are relatively cheap to buy and replace. So building your own and programming it hasn’t been necessary. Where as 3d printing was completely in accessible before the reprap movement. 3D printing software is open source as it is motivated by people wanting to build their own machines that could build machines. Something you couldn’t easily buy.

Framework still don’t have open firmware