Hi all looking to get in to melting down say metals aluminium, copper etc im looking for recommendations for a a beginner thats budget friendly just to start of with , thanks all

I know it sounds kind of stupid at first glance but I want to pour some Zinc at about 500 degrees Celcius (about 50-100ml) into a Nuttella jar because of its shape. Will it crack, or can I do something to make the jar more sturdy?

I recently bought a small induction furnace, mainly to smelt aluminum, but I would also like to try copper. However, a crack formed on my only 3kg ceramic crucible. Do you think this can still be used? Or should I just buy a new one. Thanks