I have used remelt from Alumilte but came across the same thing probably from the manufacturer called composimold found here:
They also have a putty but I haven’t given that a shot yet. One note try not to overheat it or it will bubble. The cooldown is pretty slow so you can degas it in a standard vacuum chamber if needed.
I find it handy for banging out extra copies of parts in various urethanes or even silicones since neither stick to the mold material. I still give the mold a quick hit of a release like the manns 200.