Using silicone molds and polyurethane (PU) resins, it is possible to get very close to production-quality parts with vacuum casting. The tooling is generally made from silicone, which is very cheap compared with a steel injection mold tool. A range of materials are available and it is possible to do over molded parts, as well. Vacuum casting is only really competitive for smaller production runs around <100 parts or for larger parts where tooling costs would be high. 
Because of the lower upfront investment in tooling, vacuum casting allows testing a number of different designs before settling on a final iteration. Advantages over 3D printing include better and more varied options for surface finishes, a larger choice of materials and the ability to color parts without painting. 
Vacuum casting can also produce rubber-like parts that offer more durability than the 3D-printed alternatives. 
Vacuum casting is a quick option for low volumes of parts, but because of the labor involved, if part numbers start climbing above 50 pieces, the cost and lead time will start climbing, too.