zlacker

A FDM 3D printer is mechanically relatively simple; it's more akin to a 3D plotter: it's a vector thing. Household 2D printers do bitmaps.

There's 3D bitmap printers as well, like the SLA resin printers and laser sintering.

The bitmap thing at a high resolution requires higher precision equipment than a typical 3D printer which makes it more difficult to do as a hobbyist. Not impossible, but a factor.

>>ragebo+(OP)
Yes, I learned a lot about inverse kinematics when I was upgrading my 3d printer to be used as a 2d plotter (simply printing a pen holder and figuring out how to create the GCODE).

Drawing a circle with X/Y stepper motors is more involved than you'd think. You can either resolve every step with a high resolution (command the steppers to move fractions of a millimeter at a time), or approximate the curve and let the printer do its own IK to figure out how to best represent them in real space.

Both have advantages/disadvantages. The high resolution approach can product more accurate lines, but can sometimes require more computation than the little MCU is capable of (which can cause inaccuracy of plotting as the printer fails to keep up)