You get this set of Flowers soap pull through tools.  If you need string holes please leave me in comments.  FIt a 3" PVC mold.   Its designed to fit 6/32" to 1/4" or #6-32, #8-32 Metric All thread rod. Can be found at your local hardward store.

Pull Through Soap Mold Tool Flowers fits 3" PVC pipe Can be cut 2.75"

Size in Inches