Incremental sheet metal forming is becoming an attractive technology for fast prototyping and small batch production of sheet metal parts. The majority of investigations are focused on the use of a rigid tool to incrementally form the sheet metal into a final shape. An interesting alternative is to substitute the rigid tool with a high velocity water jet (WJ). The comparison between using a rigid tool and a WJ shows that each method has its advantages and disadvantages. This investigation is aimed to identify the most influential parameters affecting the forming process through experimental comparison of the two observed methods. Technological windows based on non-dimensional values and relevant process parameters like force on the rigid tool and water pressure were defined.