For modeling I use Lightwave modeler. I did a boolean subtraction of the bunny model from a box for each side. I then used the knife tool to bring the edges of the mold closer to bunny shape. I used stencil and smooth shifting to create the alignment pegs.

what about tumbling and turning the mold like everybody else?

More bunnies per hour as you save the time in the freezer.

You would need to find a solvent for PLA that works like Acetone for ABS to help make a smooth crevice free surface. I'm not sure how ABS Acetone mixture would stick to PLA.

Yeah if you created a solid slightly scaled down print of the bunny, with mounting pegs (maybe near the bottom, since it looks like you pour molten chocolate in the bottom), then you could put the solid small bunny inside the two outer mold halves, clamp it together, and be able to pour chocolate in the space between to make a hollow bunny.

Of course as described you couldn't get the solid plastic part out! :) maybe if you sliced up the bunny into tall smooth slices, so that you could slide out the inner core, then have remaining support pieces pull away toward the center, leaving just the hollow chocolate.

(I think they used pressu
rized air or gas with the real ones?)

There are clearly small pegs to help align the mold.

Yes, but you need to be sure and fill in all the crevices with abs acetone mixture.