You have it right, as part of a agreement with fellow prop makers back in the 80s, I was to make some kind of change so that IF some of my models ended up on auction they could be spotted as fakes.
I also found it hard to paint or keep tape on a model so added evergreen plastic to replace the tape and make it much easier to paint the details.
These details became tells.
SO I did the plastic for tape on: all the movie props that had tape details.
And yes I cast the razor foil as buying a razor for each model made NO sense.
Even one razor for three.