Wooden memory chests that hold more than ashes, room for photos, letters, and small keepsakes alongside the urn itself.
Most of these take a full adult set, which at about one cubic inch per pound of body weight means roughly 180 cu in for a 180 lb adult, with a separate space for the things that came with them. They read as a box on a shelf rather than announcing themselves as an urn, and that is exactly why some families choose one. Chests are usually wider than a standard urn, so measure carefully if the piece has to fit a niche.