I find the term "half-post" to be really confusing. We have had long discussions about this years ago. The descirption "half-post" came from an early bottlemaking term.
I have been trying to replace it with "partially cased" which does for all other items as well.
My first thoughts on this - before I enlarged it, that it might be Benny Motzfeldt for Randsfjord.
But the colours of the bottom part are wrong and it's not a diamond shaped inkwell.
And I'm not sure if she put rims on.
I've got the book on her, I'll have a check for you and see if this is one of her designs.

(I have editied this post to change my booboo of saying Hadeland instead of Randsfjord.)