This recipe shows you how to make glycerin soap base. It makes a moldable base (purged of all lye and oils) that you can make into many shapes and colors.
Keep the heat at medium for a few hours, much like making crockpot soap. When the glycerin soap mixture reaches the gel phase, it will look translucent like petroleum jelly. Stir once in a while, but not all the time. If it gets too thick, you can use a potato masher. I have a stainless steel one I use just for this.
Be very careful as alcohol has a low flash point and can start on fire. This is why I prefer the crockpot to the stove for heating. You may need to mash the soap up some. Do a bit at first, then do more in a little while. If you mash too much at once, you may get a lot of suds. This process can take a few hours, so be patient.