That is very interesting Ivo. Can I ask the nature of the evidence that Rimac was produced at Boom. It's a question I've also been asking!
The finish is more polished and the weight of the Rimac glass is much heavier than the rest of Boom's output though, isn't it? Was there a 'different' recipe used?
Fascinating Kathy. The design idea is certainly very similar. Some of these forms are also found from bohemian factories though, so perhaps we should be seeing them as 'semi-traditional' rather than as the handwork of a named designer?!
The rosebowl/pot-porri bowls with a stepped upper section on a bowl-shaped base are a good example I think. Virtually identical in design they can be traced to at least dozens of factories. If they are not distinctive or marked then they may well prove impossible to trace, because they are almost 'generic' to every glass producer of the period. Hyacinth glasses have similar problems with identification.

I've been learning more and more about the history of designs and the production of moulds. We know that glass blowers moved around a lot, and they certainly didn't see much problem in taking the 'designs' with them, or remaking moulds to replace those that had been left behind at a past job.
In general terms the idea of protecting a design internationally is a post-war phenomenon.
I am in the process of redoing my site, and there will be much more information there in a few weeks time.
One of the features on my site is a 'glass ID quiz' which reflects what I am learning about identification, and I would love to have a picture of one of your pot-pourri vases to include in the new quiz!