Perhaps not schleiergraphit itself, but still possibly P&P and perhaps Horst Tusselmann?
I do have a large (marked) Unikat P&P charger with a mass of graphite-surrounded small bubbles and big gold filled bubbles, in the base.
Completely off topic, but I have an id to report to Ivo.
Do you remember the little studio glass bottle with the "knot" in the neck you gave me? It's by Ahmed Fouad, Alexandria.
Funnily enough, I already had two other small pieces he made. I bought them in Germany.