In this area the remains come from the crematorium in a standard plastic box inside a cardboard box. Most of the urns I've built are sized to take the plastic box rather than the contents. This makes for a larger box but keeps the family from having to handle the plastic bag containing their loved one. I've got one for reference and if you need I can send you the dimensions.
Cliff
That's how my parent's cremains are currently housed a few feet from where I am typing this. (still need to arrange for the memorial service and interment at the local National Cemetery) They were handled in Florida and sent north to me.
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The most expensive tool is the one you buy "cheaply" and often...