I've always save the original cap each bottle is shipped with. I take out the pump, put on the cap, tip the bottle upside down and place it in a large coffee mug or something that will hold it upright. I put it in linen closet & take it out & put it outside of shower when I'm going to cleanse.
I save a 32 oz bottle that may have a smidge of WEN left in it and fill it with a couple cups of water. Into the bottle I will place the plastic tube that you can pull away from the pump that usually still has CC adhering to it. I shake the bottle, letting the water get every bit of CC off/out of the tube. Then I add a couple of pumps of styling cream, shake again, maybe a couple of drops of oil, shake..shake..shake again. Voila! I use this to refill my little RTM spray bottles that I keep in my pocketbook, my car, my bedside, etc.