I have been successful making molds with amazing remelt, but I made a plaster cast of a hand that I want to make into a candle mold and the remelt isn’t flexible enough. What products would you suggest? The hand is in a fist so there are a lot of dips and crevasses.
I'd go with one of the High Strength series as the mold, HS-3 is the softest and most flexible of them. Pretty much any liquid mold material will pick up the finest detailing as it will get into every little crack, crevasse, and dip you want and some you don't too. Also depending on how big it is, be sure to plan on how it will come out of the mold as you might need to do some pulling and stretching to get it out.