My interest in them came from wanting to know more about the last stage of such giants as Eversharp and Esterbrook.
Anyway here is a recent catch from the bay. It is a salesman case with Eversharps BPs and MPs.
I would love to hear about these writing instruments, when they were sold etc.

On the left a desk BP, followed by several versions of the "10,000 words" BPs and MPs.
You can read about the 10,000 fountain pen here.

The red and the black on the left are called "Fountain-ball"

All the BPs have the retractable pocket clip,
similar to that of Zepelovitz
(which I believe was bought by Sheaffer see here)
If anyone has more information about the clip mechanism, I would be very intersted to hear about it.

The tiny bullet shaped items appear to be refill carriers.

