Metropolis Design and Prototyping is a full service product development and prototyping firm. Since 1989 we have been helping our clients grow their business by transforming ideas into successful products. Keeping design, prototyping, and small-run manufacturing under one roof guarantees better quality control and faster turn around times.


RTV (room-temperature vulcanizing) molding is the process of making soft tools with silicone rubber.

The process starts with a master model, usually created on one of our rapid prototyping machines. Once the master part is finished and detailed, we cast liquid silicone in a form to create the mold. The mold can be complex with multiple parts, parting lines, hand pulls, threaded inserts, and over molding; or it can be very simple, with one piece cast in an open mold.

Several factors influence the approach we take to guarantee the best results, including:

-Desired surface finish: gloss, satin, matte, textured, etc.
-Part geometry: are there undercuts or pulls in the part?
-Durability: how many parts are required from the mold?

Standard lead time for rtv molds is four days. however on very simple parts, three days is possible. We guarantee our molds for 25 casts when using rigid urethane; soft elastomeric urethanes generally extend the life of the mold.

The greatest benefit of RTV molding and urethane casting is accuracy. Every visible feature of the master part will be replicated in the resulting cast. The process does involve minimal shrinkage which must be taken into account when high dimensional tolerances are required.