Ohhh nice! I will have to press some of mine too so, good to know that Mineral makeup works for pressing! ... only will have to find some metal pan now...
Mineral eyeshadows can't be pressed like MAC pigments since there are no binders. Semantje used mixing medium + alcohol + jojoba oil, and some people suggested hand sanitizer.
I successfully created several palettes with Pure Luxe and TKB pigments using a l'oreal face lotion, however it didn't work at all with the She Space pigments I tried to press, weird...
Fyrinnae makes a powder modifier to press loose eyeshadow. Fyrinnae It is worth a try but with their insane processing time you probably won't get the item for a couple months.