Hopman, some questions about the lens you require. Do you need just the glass lens OF do you need the lens and the brass threaded rooo sealed housing too. If it's just the glass lens, this will be simple to replicate because it is a single crown glass lens. If you want to have one made, I will give the details of a lens grinder and loan him a lens.

Beter still, get 5 made then selll the remainder to cover your costs!