Simple test print to test z-wobble on an elegoo mars without wasting too much resin.
Thin wall so that it can be printed flat off the vat.
X,Y marking as to allow to discern which axis are affected by the wobble.

I printed this and it was useful, somewhat. If you have wobble due to a misaligned lead screw this will show it. However, if your wobble is due to other things, like the bearings inside the stepper this won't show it. The model is so thin that the forces involved are small so it doesn't strain the stepper assembly.