Any additive 3D printer can do variable layer thickness. It just needs the software to adjust the amount of plastic fed to the print head, according to how thic

Any additive 3D printer can do variable layer thickness. It just needs the software to adjust the amount of plastic fed to the print head, according to how thick the layer should be, and lower the bed less for thinner layers. Layers that vary in thickness are trickier. It seems like any additive printer should be able to do them given slightly smarter software and a pointy nozzle, but controlling temperature in a pointy nozzle at varying flow rate is not simple. The heating element is far away from the pointy end, and heat arrives at the tip both by conduction in the metal and also by physical motion of the melted filament medium. You need to vary the current to the heater so that the tip stays at the right temperature at all the different filament flow rates. Changes to the current have to happen well ahead so the right amount of heat actually reaches the tip, by the two routes, sometime later. You are also changing the feed rate of the filament, so it is carrying heat down at varying speed. The point is cooling by radiation and convection, the latter which varies by how fast the tip is moving, and the ambient temperature.