/u/amifufu has previously answered Before we had things like Formula, how did infants whose mother died in childbirth get the necessary nutrients that are in breastmilk?

/u/mimicofmodes has previously answered In older days let's say before infant formula was invented how did lower class/poor families tend to/feed newborns in circumstances where the birth mother died during labor and couldn't afford/ get a wet nurse.

/u/Superplaner has previously answered Before specially made baby food, how did the people of your era feed their babies?

More answers remain to be written on this very popular topic.

Your fictional blacksmith must have been the most hated man in all the village if not a single recent mother was willing to help him wet nurse an infant. Realistically, that is what he would have sought to do. Find a woman who would, for payment or out of the kindness of her heart, agree to wet nurse the infant. Short of that, the other option was dry nursing and it really was never seen as anything but an absolute last resort.

Dry nursing did, to the extent records exist, consist of making basically what people thought an infant needed into a milk-like substance and feeding it to the infant. Recipes varied wildly between countries, regions and even households but generally speaking the basis for it was whichever milk was available with additions of water, some form of sweetener and water.

If you want a semi-realistic recipe that wouldn't leave your fictional character with rickets and scurvy, perhaps milk of some sort, honey, water and either fish oil or citrus juice of some kind. Even with that though, if you want to be realistic enough to go bother a bunch of dusty historians about it, you should probably give your character a deficiency disease of some kind, or several.

If you want more information and sources you can find it in my previous post the FAQ-finder linked.