I just got followed by this company called lunavast printers on Twitter. They make a DIY printer kit that supposedly combines 2d inkjet printing with 3D FDM printing. From what I read, they have two method of printing, but essentially what is does its lay down a layer of filament, and then goes back over the gcode steps for that layer and then prints cmyk color ink on the layer.

I I am not sure what the results would look like as I would imagine that it could either be a messy proposition or lead to low resolution color prints due to color ink simply being laid on top of the extruded filament.

Lunavast.jp is their website if you're interested in looking. The site is in English. I should note that I am in no way affiliated with them.