How to Cast Metal Parts from 3D Prints？

3D prints can be used as patterns to create metal parts through several established casting methods. Here are the main processes:

Method 1: Lost PLA/Resin Casting (Investment Casting)

The most popular method for hobby and professional use.

Process Steps

1. Print Your Pattern

• Use PLA, ABS, or castable resin

• Print at 100% infill or low infill with thin walls

• Add sprues and gates to your design

• Smooth the surface if needed (sanding, resin coating)

2. Attach Sprues & Gates

• Wax sprues connect the pattern to the pouring cup

• Gates control metal flow into the mold

• Vents allow gases to escape

3. Invest the Pattern

• Mix investment plaster (silica-based)

• Pour around the pattern in a steel flask

• Allow to cure/harden (30–60 minutes)

4. Burn Out the Pattern

• Place flask in a kiln

• Heat slowly to burn out the plastic completely

5. Pour the Metal

• Melt your metal (aluminum, bronze, silver, gold, brass)

• Pour quickly into the hot mold

• Optionally use vacuum or centrifugal casting for better fill

6. Break Out & Finish

• Quench or cool the flask

• Break away investment plaster

• Cut off sprues, clean, and finish

Method 2: Sand Casting from 3D Printed Pattern

Good for larger parts and simpler geometries.

Process Steps

1. Print a solid pattern in PLA or resin (no infill needed)

2. Pack sand around the pattern in a two-part flask (cope & drag)

3. Remove the pattern carefully — leaves a cavity in the sand

4. Pour molten metal into the cavity

5. Break out the sand mold after cooling

6. Clean and finish the casting

Pros & Cons

Method 3: Vacuum Casting (Silicone Mold)

Best for small batch production of detailed parts in zinc alloys or low-temp metals.

Process Steps

1. Print a master pattern in high-res resin (SLA/DLP)

2. Build a silicone mold around the master under vacuum

3. Remove the master after silicone cures

4. Cast metal (usually zinc, pewter, or low-temp alloys) into the silicone mold

5. Demold and finish

Method 4: Ceramic Shell Casting

Used for high-detail industrial and art castings.

1. Print pattern in castable material

2. Dip repeatedly in ceramic slurry to build a shell

3. Burnout the pattern in a kiln

4. Pour metal into the ceramic shell

5. Break away the ceramic after cooling

Choosing the Right Method

Tips for Best Results

• Surface finish your print before casting — sanding or resin coating reduces finishing work later

• Design sprues into your CAD model from the start

• Account for shrinkage — metals shrink 1–5% on cooling

• Preheat your mold before pouring to prevent cold shuts

• Use proper PPE — molten metal is extremely dangerous

Common Metals Used