When this fits the 403, then i'm interested in the STL.
I've found this one https://www.thingiverse.com/thing:264268 but indeed there is no way to attach that other than tape, yours looks nice!
I'm new to this matter and unfamiliar with Kamstrup, but from my research i learned that they use 'wireless m-bus' technology.
So i wonder; would there be a way to ready live meter data over the wireless m-bus protocol as well? https://github.com/weetmuts/wmbusmeters would that be worth the trouble of trying or is it secure somehow? Someone already did?