I've been making my laundry soap for a couple of years. I like it. It does just as well as the store brands (if not better, but I'm not guaranteeing laundry miracles!), and it's definitely less expensive.
There are a number of recipes for both dry soap and "wet" soap, but the main ingredients are usually the same. I make mine on the stove; it took me quite a while the first couple of times, but now I have it done in 15 minutes.
1/3 of a 14-oz. bar of Zote soap, or a whole 5-oz. bar of Fels-Naphtha Soap (I find that Zote is easier to grate, and I like the pink color)
1/2 c. borax
1/2 c. washing soda
A 2-gallon bucket (I use a clean cat-litter bucket because it has a top)
Grate the soap and put it in a large pot.
Add 6 cups water, and heat the mixture until the soap melts.
Add the washing soda and the borax, one at at time (I usually reduce the heat a bit, because the mixture will start rising to the top of the pot). Stir until each is dissolved. Remove the pot from the heat.
Pour 4 cups of hot water into the bucket. Add the soap mixture to the bucket and stir.
Add 1 gallon plus 6 cups (22 cups in all) water. Stir.
Let the soap sit for 24 hours. It will become a semi-gel - somewhat solid, somewhat watery.
I use 1/2 cup per full load. This is a low-sudsing soap.