This is the simple height-map Tux image I’d been using for the chocolate molds:

But the poor critter looks a bit flattened:

The final result is tastier, but gives off a roadkill vibe:

After a few tweaks to the image, now he has a radial gradient on his tummy, his right flipper extends forward, his feet have webs, and his smile looks radiant. The gray levels now extend over a larger range with a bit more separation, with the intent that he’ll now be 5 mm thick:

Converted to a solid model in OpenSCAD:

In his STL file garb, he’s lookin’ pretty good:

Next step: plastic!