Keep in mind this is not a detergent safe for using as direct irrigation on plants from a greywater system as it contains borax. It is, however, wicked cheap. If it has funky results over the long run, I’ll let you know.
1 bar of Fels Naptha
1 box of Borax (20 Mule Team)
1 box baking soda
You won’t use all of these, but they are the quantities you buy in and they will make you several batches of detergent.
Grating soap, regardless of how much it looks like cheese, is much harder than grating cheese.
But, grate 1/3 of that sucker.
Add 6 or so cups of water in a pan and heat it up until the soap gets all melty.
Add 1/2 cup of baking soda and 1/2 cup of borax. Stir until everything dissolves.
Take off stove. Put ~4 cups of hot water into the bucket you’ll store the soap in (bucket needs to be at least 2 gallons large for this adapted recipe)
Pour in soap mix and stir. Add 22 cups of water and stir.
Let it sit for ~24 hours and it will turn into a somewhat liquidy gel. 1/2 cup per load will do the job.
I exchanged 2 cups of water for vinegar since that acts a a whitener. If it ruins the detergent since it reacted partially with the baking soda, I’ll let you know, but it hardly fizzed at all wheni first put it in the bucket.