I’m getting ready to make “soap on a rope” gift soap for family members. The bars will be 2.5” x 3.5” x 1.5” and made from a lard-rich recipe that won’t be gelled. I will be using a small slab mold. I plan to run braided cord through a hole at one end of the soap. I’m not sure how and when to make the hole. I have some plastic straws in the house, but I don’t know if the plastic is heat resistant. I can test that by heating them in water. If they are heat resistant, should I just “glue” them in place in advance?