Please, please, do not perpetrate the oh-so-common error of one copper plus one tin yields one bronze. For starters, 1:1 is not the correct ratio; 3:1 or 4:1 copper to tin would be closer. But the really infuriating part is the 50% metal loss. If you must have one ingot each of copper and tin for your bronze recipe, at least make it yield TWO ingots of bronze. Losing 50% of your metal is a huge incentive NOT to make anything out of bronze.
I recommend being able to use fractional amounts of base materials like ore, so you can make exactly 1 ingot, e.g. with 0,8 ingots of copper plus 0.2 ingots of tin. https://playnightingale.ideas.aha.io/ideas/RRFEEDBACK-I-502