https://www.youtube.com/watch?v=jABVTyTq8KQ
This is a Cadogan teapot that can be 3D printed.
per https://collections.vam.ac.uk/:
"The shape of this teapot is known as "Cadogan" and it was copied from a Chinese porcelain wine-pot in the collection of the Earl of Cadogan. It was filled upside down through a tube running from the base into the upper part of the interior, so that it can be turned the right way up and no liquid will escape"
I've confirmed it will work scaled down to 25%, which has a print time in a little over an hour.
Upside_Down_Teapot.STL | 147.7KB |