We've now had more than a few posts about pen knives (ironic, that there name...) done in plastics known from old fountain pens. One day I'll collate the links, but not tonight, too tired (pocket knife site search via google or via FP Board's search engine should get many). I was very happy to acquire recently a knife done in the plastic (or close to it) known from the 1940's striped Parker Duofolds. The black stripes might be a smidge thin, or... is that just from lack of wrapping into cylinder. Now where is my Wearever Pacemaker pen...
As mentioned in the other threads, most of these are believed not to have been issued by the pen makers or with the pens as sets. Just a happy reuse of plastic by the plastic companies in other settings.
regards
david