Making this laundry detergent reminded me of running my hands through beach sand, without the danger of getting it stuck in my underwear. Use a wooden or plastic spoon if you don't want to get your hands dusty. For an ordinary load of laundry, use 1/8 cup per load. You can use any plain, nonscented soap. Most online recipes recommend Fels-Naptha. I couldn't find it in my grocery store, so I used Octagon All Purpose Bar Soap, and it worked out well.
Grate the soap using a handheld or electric grater. Combine all ingredients and store in a plastic container with a lid.