The next time you are in Germany, make sure to get yourself down to Bonn to check out the Calculator Museum. Or, you can just visit their website.
http://www.arithmeum.uni-bonn.de/en/home/
The museum is closed on Montags.
I’m not exactly sure what a Theutometer is, but it seems to be available in their giftshop, and I would gladly accept it as a holiday gift.