Its too expensive and difficult to make for a toy or most common tools.
It serves no purpose as a weapon. Far too costly, wouldnt do much damage, no point in all the different size holes AND external rings around the holes, others cheaper and more effective, etc.
Shows no wear, not a tool. Even soft materials would eventually wear on the gauge. Too fragile for anything to be worked on it.
Apparently used for a specific period of time then abandoned.
Is made of metal but isnt made of metal to resist use damage suggesting that it had to be something that once made was resistant to change and damage and could be made to meet predefined specifications.
Odd inconvenient size and shape for most field applications.
All known things considered I would think this has to be something along the lines of a command/diplomatic level encryption device.
That doesnt explain the German one very well but as many have pointed out, a spaghetti gauge and a range finder are very similar tools but that doesnt mean they are used for the same thing.
Good post.