How many Nema17's could an A4988 run?

Say if I were to build multiple delta printers and wanted to run them all at the same time printing the same thing, how many could run off the same electronics? Could I run 4 steppers off the same controller?

I am under the impression we don't use all the torque a Nema17 can supply and delta printers are even lighter on the motors...?

In theory with the right motors / right voltages / right torques, you probably could run a hundred motors on an A4988. They would not run very fast or turn very hard at all.

The idea on a Delta usually is to go mighty fast. That's going to take torque to speed up / slow down. Next up would be that they often use high current motors (for what ever reason). That's the wrong motor if you are going to parallel a bunch of them up. You want to start with low current motors.

Best approach is likely a compromise. Get some 0.5A motors and run them at 1/2 current. Put a 32V supply on your control board and a fan on it. See how far you can go.

With higher voltage driving the motors you could also wire them in series. You might get a bit less speed but total torque would be better. Or some combination of series and parallel.

Series wired motors can (but may not) get you into some interesting damping issues. I'd stick with parallel wired stepper motors.