Although a vacuum pump and chamber will make your life easier if you are making silicone molds on a regular basis, it is a lot of money to spend on equipment.

Some of our mold makers who do not own vacuum equipment claim that the following method works well to minimize bubbles in their finished mold;

After their silicone rubber is mixed, they will brush a thin coat over their model and then pour the balance of the mixture behind it (off model) over their model.