DIY Projects & Crafts Bath Bombs and Soaps Homemade Soap How to Make Homemade Glycerin Soap Beautiful soaps are easy to make with a melt-and-pour technique—just add food coloring and mold using recycled milk cartons. By Martha Stewart Editors Martha Stewart Editors Facebook Instagram Twitter Website An article attributed to "Martha Stewart Editors" indicates when several writers and editors have contributed to an article over the years. These collaborations allow us to provide you with the most accurate, up-to-date, and comprehensive information available.The Martha Stewart team aims to teach and inspire readers daily with tested-until-perfected recipes, creative DIY projects, and elevated home and entertaining ideas. They are experts in their fields who research, create, and test the best ways to help readers design the life they want. The joy is in the doing. Editorial Guidelines Updated on May 13, 2021 Share Tweet Pin Email Learn how to make soap using glycerin. Glycerin is usually sold in large blocks at crafts stores; to melt it, cut it into small cubes that will fit in a microwavable bowl or measuring cup. You can also make multiple mini soaps by using ice-cube trays as your molds. What You'll Need Materials Clear Glycerin Soap Food coloring Bench Scraper Coffee stirrers Clean milk or juice carton Petroleum jelly Instructions Heat the glycerin in a microwave on high, stirring at 15-second intervals, until it's completely melted. Mix liquid food coloring into a bowl with a coffee stirrer. (Note: Food coloring is very strong, so use it sparingly.) Coat the inside of the milk carton with petroleum jelly. Pour in melted glycerin; let cool completely—about two hours. Tear away carton, and, using a bench scraper, slice block into individual bars.