I’ve published a paper about gray scale printing in the journal Computers & Graphics
3D hatching: linear halftoning for dual extrusion fused deposition modeling.
The accepted manuscript can be found here: https://arxiv.org/pdf/1805.01375.pdf
The final paper can be found here: https://dl.acm.org/citation.cfm?doid=3083157.3083163
This is an extension of the conference paper called
3D hatching: linear halftoning for dual extrusion fused deposition modeling
https://dl.acm.org/citation.cfm?id=3083163
