Here are a couple of rare and unusual pens, Parker Vacuum Fillers from around 1932-33.
The pen above is a short model with a ribbon ring fitting; the laminated celluloid is opaque, and the barrel and section are one piece. The nib is two-tone, the jewels are striped. The pen below is large, with a black section and black jewels. The cap is a laminate of red and translucent blue, while the barrel laminate is transparent. The nib is two-tone.
As with any new product, Parker's first year of Vacumatic production saw extensive tinkering and experimentation. The name changed from Golden Arrow to Vacuum Filler to Vacumatic; many different configurations were tested, and eventually most (including the examples shown above) were dropped. The experimentation was not just to find out what consumers wanted most; clearly, there was also some learning to be done on the production side as well: gold-filled trim on Vacuum Fillers is much more prone to flaking than on later pens, for example.