Need fifty copies of that 3D printed whirligig you’re so proud of? It might be faster to just cast copies by using the 3D printed model to make a mold. [Micah] found himself in this situation and managed to cast one copy every 10-12 minutes using the mold seen above.
With the object in hand, you need to find a container which will fit the mold without too much waste. The bottom half of the mold is then filled with modeling clay, a few uniquely shaped objects to act as keys, and the model itself. After getting a good coating of release agent the rest of the mold is filled with a silicone rubber product which is sold for mold making. This creates one half of the mold. After it cures the clay and key objects are removed, everything is sprayed with the release agent, and the other half of the mold is poured.
Now your 3D object can be copied by pouring two-part resins in the to shiny new mold.