Fix it Dad has triumphed again. I tried to fix some of the kids lego with some casting resin which has been stored in the shed for the last 10+ years. I’m just coming to appreciate that the stuff does have a sell-by date as no matter how much catalyst I add it isn’t getting beyond the gluppy mess stage. Ive removed as much as possible manually but am still stuck with a sticky residue.

Does anyone know of anything I can use to remove the resin without dissolving the plastic/my hands?

Lego is ABS I think, so acetone is out. You could try meths?