mass - How can you weigh your own head in an accurate way?

I read some methods but they're not accurate. They use the Archimedes principle and they assume uniform body density which of course is far from true. Others are silly like this one:

Take a knife then remove your head.
Place it on some scale
Take the reading
re-attach your head.

I'm looking for some ingenious way of doing this accurately without having to lie on your back and put your head on a scale which isn't a good idea.