How to Use Rhino 8 to Create Manufacturable Silicone Molds

Rhino is the Swiss Army Knife of industrial design and the primary tool used by YiKe Studio engineers. Many beginners create 3D models that look great on screen but are physically impossible to demold. Today, we’ll guide you through the first steps of "Design for Manufacturing" (DFM) using Rhino 8.
Step 1: Boolean Difference (The Negative Space)
Mold making is essentially creating "negative space."
• Action: Create a block (your mold base) and intersect it with your design object. Use the BooleanDifference command to subtract your object from the block.
• Check: You should now have a cavity shaped exactly like your object.
Step 2: The Lifeline — Draft Angle Analysis
This is the most overlooked step by beginners. Vertical walls are hard to demold and can tear the silicone.
• Action: Use Rhino’s DraftAngleAnalysis tool.
• Rule: Even with flexible silicone, we recommend a draft angle of at least 1-3 degrees. If the analysis shows red areas (undercuts), the mold might lock onto the object. You must adjust the surface curvature.
Step 3: Accounting for Shrinkage (Scale)
Both silicone and resin shrink slightly during the curing process.
• The Math: Liquid silicone typically shrinks by 0.1% - 0.3%.
• Action: Before creating the mold cavity, use the Scale command to enlarge your original model by a factor of 1.003. This tiny adjustment is the difference between an amateur hobbyist and a professional engineer.
Step 4: Parting Lines & Registration Keys
For complex figures, you often need a two-part mold.
• Tip: When splitting the mold block in Rhino, do not use a flat plane. Design "Keys" (interlocking cylinders or pyramids) along the parting line. This ensures the two halves of the silicone mold lock together perfectly, preventing misalignment lines on your final product.