Need Robocasting & FEF 3D printers information

Hi, I am doing research on material extrusion-based 3D printers trying to summarise printers structure and principle, right now I've finished investigating FDM, however, since the robocasting and FEF 3d printers are not as much as FDM, I am having a hard time to find more info about it. Does anyone have any idea where I could find:
1, working principle (basically I want to know the general structure of the 3D printers)
2, printing details, (for example, in FDM the head temperature, extruder speed, bed temp etc. which are critical to the process)
(or maybe some famous printers?)
I want to collect this info for generating a general model which could cover all extrusion based printers.