Wow, it's hard to believe this forum hasn't been used in years. To me trench art to me has always been fascinating because it was made with the hands of a person, a military person (often a p.o.w.), not some machine. A literal labor of love as a hobby, or to maintain ones sanity or as a gift for a loved one back home.
This is an ashtray from a Japanese Artillery Shell ash tray, could be Series 3, 1941 (I'm no expert).