Chalk objects: 3D Printed or Molds?
Chalk, as a ceramic substance, could be printed with a paste printer and if the substance can hold its shape during drying for a couple of hours.

It might be easier to use a flexible filament like TPE or TPU to print a mold in which the paste can cure slowly to a point it can be safely removed. These filaments make release easier as one can flex them away from the printed object.

Another option could be vapor smoothed ABS and a tapered shape so that the object has no undercuts and easy paths only. If one adds a pusher rod place, which is closed by a plug during casting the chalk and can remove from the back after casting, removal gets easier as air can flow in from the back through the removed plug. It can also be used to use a pen or similar obect to gently release the item with light taps.