I went to the Lego store yesterday and assembled a model of my soap dish. It really doesn’t look too much like the Sketchup version, does it? And it doesn’t hold soap very well, either.
But the basic process is to dunk the model in resin and let the resin harden into a mold. Then pour plastic into the mold to get the production unit. Using lego bricks to make the model is one way. I think I’ll try clay next.