Perhaps this is too mundane a subject for this board, but I will post in the hope that someone can guide me to a source.

My understanding is that certain U-boats had a "portable" toolkit for internal, operational maintenance. It included a milling machine, lathe, etc. for repair of critical operating components and fabrication of key parts if needed between yard repairs.

Supposedly, this was quite the "gizmo" with all these discrete power tools that rolled up into a compact unit for movement throughout the craft.

I don't have the proper name, nor a single photo, just the description of someone who "saw one somewhere".

ANY guidance will be appreciated.