A "Pourable" mold rubber is mixed and poured over your original model.
Consider this method if your model is;
Advantages/Disadvantages - Pourable molds are easier to make vs. brush-on molds, requiring less labor. They also take less time to make, meaning you will have a mold you can use same day or early next day; however, you use more material to make a mold so your material cost is higher.
An easy to use pourable mold rubber is our Mold Star® series (https://www.smooth-on.com/product-line/mold-star/), which are easy to use, low viscosity platinum silicones with a convenient mix ratio of 1 part A to 1 part B by volume.
A "brush-on" mold rubber is mixed and brushed onto your original model in layers. After all layers cure (usually overnight), a rigid support shell (also known as a "mother mold") is applied the next day.
Consider this method if your model is:
Advantages/Disadantages - Less material, over all, is used to make a brush-on mold so your material cost is less. However, brush-on molds take more time and effort to make (much more labor vs. a pourable mold). Making a brush-on mold is also more challenging and therefore requires a lot more pre-planning.
A simple to use brushable mold rubber is our Rebound® series (https://www.smooth-on.com/product-line/rebound/), followed by a Plasti-Paste® II (https://www.smooth-on.com/product-line/plasti-paste-series/) for a rigid support shell/mother mold.