Lately I've needed to use one batch of soap to make a variety of soap scents and colors. This is a little tricky, although this fiddly soaping feels more like cooking and is very fun. If I made six separate batches of soap, to get six different scents, I'd be making soap for days, and it would cost a lot. And, I'd have more soap than I needed for my inventory at the time.
When you've been making soap for a while and you feel really comfortable with the stage when you're adding the lye and getting the mixture to trace, you're ready to fiddle with it. I like to allow my lye and oil mixtures to cool to about 115º F. This takes patience; don't be in a hurry. I use a stick blender to mix it, but don't be aggressive. If the temps are right, and the weighing was accurate, the mixture should start coming to an early trace after only about 30 seconds of pulsing the stick blender on low. Also, be sure to stir the mixture well with a spoon, pulling the liquid from the bottom of the bowl up -- it's usually already thickening more down there.
Watch the mixture carefully. You want to catch it at an early trace, because you need lots of time to be able to separate it into various scents, without the remainder hardening too much. I use a large stainless steel pot when I add the lye mixture. At early trace, the surface of the soap mixture should have faint swirls developing on it, and when you lift the blender or the spoon out of the soap and allow it to drip into the mixture, little dimples and indents should remain on the surface -- faint ones. Stop blending at this point! If the soap is already gloopy and will stand up on the spoon? You've mixed it too long, and it's already past the early trace. You should scent it quickly and pour it into one or two large molds.
But if you can catch it at an early trace, work quickly and pour some of the soap into a 2-cup pyrex measuring cup. (That's what works for me.) Have your scents and colorants all laid out. Add a small amount of the first scent and some colorant. Don't overdo it, since it's only 2 cups of liquid soap. Mix well with a spoon and then pour this one into your prepared mold. I place pieces of paper next to each mold with its scent name written on it, because I'm likely to forget which scent I put in which mold, and later on it's sometimes hard to tell by smelling. My nose gets weary of so much scent, and I can't distinguish.
Have a handful of clean spoons, a couple of rubber spatulas, and a few paper towels laid out too. That way you can clean out the pyrex cups quickly, and move onto the next scent and colorant without contaminating it with the previous one. I hate wasting the soap, so I really do scrape out and wipe out as much as possible.
By the time you get to the 4th or 5th scent, you'll notice that the remaining liquid soap in the pot is getting thicker, gloopier. Work quickly. I organize my colorants and scents, beginning with the lightest colorant and the most delicate scent, and working to the darkest and most aggressive. Also, do your more difficult, smallest molds first, when the liquid soap is more pourable. Save your large molds till last, when the gloopy soap will "pour" into those large ones relatively easily.
Because the liquid soap is sitting in the pot while you're fiddling with all this, it will lose some of its heat then, and it's doubly important to cover and wrap your molded soap well, so it can retain as much of its heat as possible and come to the gel stage.