OK, now that the pics are coming out, I will try to describe step-by-step.
First, I take apart a bath pouf. I don't have one to take apart, but you just find the center and cut whatever is holding it together. Some are string, some are rubber bands.
Then, I take a bar of soap, and measure about 3 times the length of the bar of soap in mesh, I double the mesh over with about half a bar length on top and bottom. Cut there.
Then fold the mesh in half. Melt the cut ends. You simply use a lighter, and heat and mash them together. Repeat until you have a small, neat end. Do not allow it to burn, it will turn black (ignore the black in mine, the neighbor decided to come say hello).
Turn the bag inside out. Snip a small opening at the folded (not the melted) end. Cut through only the outer layer of mesh.
I tie a slip knot in a piece of cotton yarn and secure a safety pin through it. Use that to thread the yarn through the mesh. If you have lots more time than me, and a sewing machine, you can sew a channel to hold the yarn in place.
Put the bar of soap in there, and tie a knot or a slip knot using both ends of the yarn.
That's it. Nothing complicated.