to help separate the pieces after the product has cured. A flange is also a metal nut component that attaches two or more metal rods together. Ladyflanges is referring to sexy legs and arms on a woman; Lady parts; Lady appendages.
A flange is a term used in sculptural mold making, it is the external “wings” attached to the outer mold
“I like the ladyflanges on her!”, “My ladyflanges are cold, give me a blanket.”