It’s actually easier with 3D printers in some ways.

3D printers:

• Only one extruder needed
• Parts are easy to source (basic aluminum extrusions, stepper motors, wires)
• There software is easy to find online and install
• The accuracy needed is pretty lax

2D printers

• Can get away with 1 color, but 4 if you need full color which gets complicated fast. Granted 3D printers aren’t much better on this front
• The parts are not easy to source. They’re often proprietary and therefore expensive
• Good luck finding software for it
• The accuracy needed for printing is far higher than 3D printing

There are open source 3D printers, and quite a few of them. To my knowledge, there are no 2D printers that are open source. At best you can find instructions on how to hack proprietary ones.