Make Composite Molds for Hollow Core Parts.ST-130 is a soluble 3D printing material. It’s main use is for making sacrificial 3D printed composite tools for hollow core parts like tubes, manifolds and ducts. The dissolvable ST-130 filament is printed to form a mold in the shape of the final desired part. The composite material is then wrapped around the mold and cured. After cure, the part and mold are immersed in a solution bath, dissolving the ST-130 sacrificial material, leaving the finished hollow composite part. ST-130 is capable of autoclave cure and is typically used with a standard triangle fill pattern to promote fast dissolution, optimize build speed and conserve material. It’s particularly advantageous for making complex hollow composite shapes, which would normally require multipiece clamshell molds that produce seams in the part. Molds made with ST-130 let you create seamless, single-piece parts in one lay-up operation.