1 cup washing soda (Arm & Hammer sells this but it can be difficult to find. Try making it yourself!)
1 bar soap - grated (I used Dr. Bronner's Almond bar soap for my first batch.) You can always use Ivory, Zote, Kirk's Fragrance-free soap, or Fels-Naptha [found in the laundry section of the grocery store] which are pretty cheap. My Walmart sells Fels-Naptha for $0.97 cents.)
Step 1: Grate the bar soap using a normal cheese grater into a container/bowl.
Step 2: Add the grated soap to the blender with along with 1 cup washing soda. Blend together until it is fine.
Step 3: Add your 1 cup Borax and blend well.
Your laundry detergent should look like this when you are all finished! I will take a better picture next time and upload it out of the blender. But it should be fine and look like what you would expect it to look like.
I use 1 Tbsp of detergent per load. You can use 2 if your clothes are really dirty.
*From learning about Borax, it heightens cleansing properties in warm water so I tend to wash my clothes on warm. I've also done loads with cold and it has worked just as well too.
Calculating the cost of this detergent for me is about $0.10 - $0.13 cents a load depending on how much I pay for the Dr. Bronner's bar soap. But if you use something cheaper, it will be like a nickel a load. Amazing huh! Now try it out for yourself!