Here was an interesting item that I found at the recent Columbus pen show sitting in a box of spare parts. Unfortunately I only found this gold plated cap alone without its matching barrel.
Here is a close-up of this cap.
Notice that it has a pattern of repeating single lines with a blank space reminiscent of the Ambassador pattern. Unlike the Ambassador, however, the lines are not accentuated in black.
Another curious item is the "75" inscription. This inscription can also be found on one other model, a variant of the 75 Flighter, though not all Flighters have this inscription.
The full FP was found at this event so I am moving this item to the unknown pattern category.