Walking! Miva (歩く! ミーバ) is a playset by Tomy. It comes with glowing slime, called a "Miva", a windup toy, and a plastic tray with two molds.
You can cover the windup with the Miva, press it into one of the two molds the plastic tray comes with, take it out of the mold and add the pink eyes the toy comes with, wind it up, and watch it walk, as it glows in the dark.
Two of the molds include a robot and a strange creature, shaped like a blob. The slime glows in the dark, since it can absorb light.