Trench Art is a term used for items made by soldiers during deployment using whatever materials are to hand. Brass casings are particularly prized in more modern times, but you can find these sometimes humble, sometimes extraordinary objects going back to probably the first armies to be sent anywhere.
WWI was a particularly rich time for Trench Art and the war with its long periods of waiting around in trenches gave both ample opportunity for creation, as well as the term itself.
I recently was able to acquire a piece of trench art where some unknown soldier used two bullets and from them created a double-ended pen/pencil combo, like a Traveler. (a particular design of pen and/or pencil where the writing tip can be turned inside the hollow handle to protect it during traveling). The two pens are engraved with small hatching and curves to cover the ground, as well as the words "Lorraine" and "1918" on one side, and a flower (Poppy?) as well as a leaf or other floral design on the back.
It's pretty amazing what these guys could do while sitting around being shelled, or waiting to be shelled.
Anyway, just thought I'd throw this out there in case some of you may find it interesting.
Andrew