Another option from Jim Stone:

Take a half pound of barley and loosely tie it up in a cotton cloth that is porous. It has to be loosely woven cotton, like old-style diapers. Loosely tie the barley in it (the barley will expand) and put it in a pot with about 6 liters of water. Boil it for 6 - 7 hours. Pour the barley water off. Throw away the barley. There should be about 4 liters of water left after boiling (a slow covered boil) If you do it right the water should be bright pink. Mix that with three liters of milk and add a pound of sugar to the final 7 liter mix. If it comes out to 6 liters still add a pound of sugar, it will not be too much. The actual good limit is 27 ounces of sugar added to 7 liters. It is supposed to be sweet. The baby needs sugar for energy. Make sure you are not a snowflake and USE SUGAR, NOT A SUBSTITUTE. Corn syrup is also permissible in the same amount but nothing else*. I'd add a couple grams of salt (just the tip of a teaspoon) to the final mix of about 7 liters and no more, it should not taste like it has salt. It should taste like it has NO SALT. Freeze what you are not going to use right away. You'll have a happy healthy baby, that recipe totally destroys commercial formula. I can back this up with hard data. That is THE RECIPE. If anyone posts a recipe more complicated or quicker or easier or more "nutritious" than that, it is a load of crap. That is the old Roman recipe that has been around for 2,000 years and it produces great results. I know this because the family used that recipe when a mother could not produce milk, it is all the kid had and the (not vaxxed) kid is sharp as a whip.

*see Litecola2's point on glyphosate in corn syrup

Another option from Jim Stone:

Take a half pound of barley and loosely tie it up in a cotton cloth that is porous. It has to be loosely woven cotton, like old-style diapers. Loosely tie the barley in it (the barley will expand) and put it in a pot with about 6 liters of water. Boil it for 6 - 7 hours. Pour the barley water off. Throw away the barley. There should be about 4 liters of water left after boiling (a slow covered boil) If you do it right the water should be bright pink. Mix that with three liters of milk and add a pound of sugar to the final 7 liter mix. If it comes out to 6 liters still add a pound of sugar, it will not be too much. The actual good limit is 27 ounces of sugar added to 7 liters. It is supposed to be sweet. The baby needs sugar for energy. Make sure you are not a snowflake and USE SUGAR, NOT A SUBSTITUTE. Corn syrup is also permissible in the same amount but nothing else. I'd add a couple grams of salt (just the tip of a teaspoon) to the final mix of about 7 liters and no more, it should not taste like it has salt. It should taste like it has NO SALT. Freeze what you are not going to use right away. You'll have a happy healthy baby, that recipe totally destroys commercial formula. I can back this up with hard data. That is THE RECIPE. If anyone posts a recipe more complicated or quicker or easier or more "nutritious" than that, it is a load of crap. That is the old Roman recipe that has been around for 2,000 years and it produces great results. I know this because the family used that recipe when a mother could not produce milk, it is all the kid had and the (not vaxxed) kid is sharp as a whip.