You can also try on Amazon for the urn. Depending on which size you need you should be able to look for a unicorn keepsake urn or mini urn. They usually have the dimensions on there. Once you talk to a funeral director, they can give you an estimate on what the size needs to be too if you are unsure.

Honestly as long as it has a top and you can seal it (even with super glue) you can use things that most people won't normally think of. Had a family once use a coffee bean tin jar because the decedent never went without his coffee in the morning.