I generally use an old Rubbermaid pitcher for mixing lye which has PP #5 on the bottom. You might have one you can use for lye. If not, ask family or check out garage sales or thrift stores. Other people have mentioned they use plastic buckets to mix lye. You just want to make sure what ever you use either has PP #5 or HDPE #2 on it. I recommend PP #5 since HDPE #2 isn't as heat resistant.