Summarize:

If you want round-shaped bars of soap, you can make a cylinder mold. Make sure you get your liquid soap ready before preparing a cylinder mold, as you'll be pouring the soap in as you go along. To start, gather your supplies, most of which you can find at a local craft store. You will need the following:  A PVC pipe A wooden cutting board Masking tape Heavy duty wax paper or baking paper Old towels A ladle Plastic wrap Wrap the wax or baking paper around the end of the pipe, making sure to cover completely so no soap leaks out. Then, take the masking tape and wrap it around the end of the pipe. Use a few layers of tape to make sure the wax paper is secure. You can also use rubber bands. Set your pipe down vertically. Use your ladle to transfer liquid soap into the pipe. Do not fill the pipe completely. Stop when you're about 2 inches (5 cm) away from the top of the pipe. Tightly wrap the plastic wrap around the other end of the pipe. Use a few pieces of tape or a rubber band to secure the plastic wrap. You want to keep the soap insulated during the curing process. Use old towels that you do not mind damaging. Soap may leak out, causing stains or odors. Wrap the mold in enough towels to cover the pipe completely, preventing outside air from getting into the mold. Set the mold aside for 48 hours, or as long as your soap recipe indicates it will take for the soap to dry. At this point, the soap should be cool enough to remove. Choose a safe place to keep the mold, away from children and animals. You want to make sure the mold is not moved or disturbed during the drying process. Once the soap is dry, you can remove it from the mold. This can be a little tricky. You should be able to push the soap through the pipe using a bottle or jar. If you have trouble removing the soap, consider lining the mold with parchment paper ahead of time the next time you use this method. This may make the soap slide out easier.
Gather your supplies. Cover one end of the PVC pipe with wax or baking paper. Fill with liquid soap. Cover the other end of the pipe with plastic wrap. Wrap the mold towels. Cool the soap. Remove carefully.