This article explores how to identify and fix common defects in vacuum mold casted parts, a precise manufacturing approach popular for prototypes and small batch production. It covers the complete vacuum casting process—from master model creation to mold making, resin casting, curing, and demolding. Common defects such as porosity, surface flaws, incomplete fills, warping, and flash are detailed alongside causes and practical fixes. The guide emphasizes inspection techniques, process optimization, and best practices to improve product quality in OEM manufacturing environments.