pickling bowl; pickle press
A container or device used for making Japanese-style pickles (漬物). Can refer to a simple weighted bowl or a mechanical press.
My grandmother makes rice-bran pickles using a pickling bowl.
This pickle press is convenient because it comes with a weight.
Compound of 漬物 (つけもの, 'pickles') + 器 (き, 'container, utensil').