You can print with flexible materials. There are some rubbery materials out there, some people tried to print with silicone as well (with a syringe, not with an heated extruder of course). But if you want to make a mold, the usual way would be to create the mold from a print, not printing the modl itself.

A ship in port is safe; but that is not what ships are built for.
Sail out to sea and do new things.
-"Amazing Grace" Hopper

Avatar image of me done by Chidori.