🎯 Lesson: Painting and Assembly
🧠 Focus: Learn how to transform your 3D prints into finished, visually striking, and functional models through proper painting techniques and multi-part assembly methods.
✅ Lesson Summary
Painting and assembly are key final steps that elevate your 3D printed models from raw plastic to professional-quality creations. Whether you’re prepping parts for display, cosplay, or functional use, understanding how to prime, paint, and assemble parts ensures durability, realism, and visual impact.
🎓 Learning Objectives
By the end of this lesson, students will be able to:
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Choose the right paint and primer for FDM and resin prints
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Prepare 3D printed parts for paint using sanding and sealing techniques
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Apply painting techniques including base coats, detailing, and finishing
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Assemble multi-part prints with adhesives, fasteners, or design-fit joints
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Identify best practices for both artistic and functional applications
📘 Lesson Content
🟩 1. Preparing for Paint
Before applying any paint, the surface must be prepped properly:
| Task | Notes |
|---|---|
| Sand | Smooth out layer lines and imperfections (see previous lesson) |
| Clean | Use isopropyl alcohol or warm soapy water to remove dust/oils |
| Apply filler primer | Spray 2–3 light coats to fill small gaps and help paint adhere |
| Dry fully | Allow 12–24 hours for primer to cure before painting |
🧼 A clean, smooth surface = better paint adhesion and visual finish.
🟨 2. Choosing the Right Paint
| Paint Type | Best Use | Notes |
|---|---|---|
| Acrylic (water-based) | Safe, easy cleanup | Best for brush work and airbrush; low odor |
| Spray paint (enamel or acrylic) | Smooth base coats, large parts | Shake well, apply thin coats, watch for runs |
| Oil-based | Durable and glossy finishes | Takes longer to dry; wear gloves and ventilate |
| Resin pigment paints | Resin miniatures and clear parts | Great for detail work; often paired with UV curing |
🟥 3. Painting Techniques
🎨 Base Coating
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Always start with a primer coat
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Apply light mist coats of your base color
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Hold spray can or airbrush 6–12 inches away from part
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Let each coat dry before applying another
✍️ Detail Work
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Use fine-tip brushes for edging, eyes, and small textures
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Dry brushing technique can highlight raised areas
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Use masking tape or liquid mask for sharp paint boundaries
✨ Finishing Touches
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Apply gloss or matte clear coat for protection and aesthetic
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Add weathering effects with dark washes, scuffing, or pigments
🟦 4. Assembly of Multi-Part Prints
Whether assembling large models or multi-component prototypes, good joints and adhesives are essential.
🧱 Fitting
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Use alignment pins or interlocking joints in your design
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Dry fit parts before applying glue to ensure alignment
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Sand mating surfaces for better grip
🧪 Adhesives
| Adhesive Type | Use Case | Notes |
|---|---|---|
| Super glue (cyanoacrylate) | General-purpose plastic bonding | Fast-setting, clean contact surfaces first |
| Epoxy | Heavy-duty bonding | Takes longer to cure but very strong |
| Welding solvents (e.g., MEK for ABS) | Chemical bonding | Melts plastic slightly for permanent bond |
| Hot glue | Temporary or large surface areas | Not ideal for precision or strength |
🛠️ Optional: Use clamps or rubber bands to hold pieces together during drying.
🔩 Mechanical Assembly
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Design parts with screw holes, snap fits, or inserts
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Use brass heat-set inserts for threaded connections in FDM prints
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Resin prints can use tiny magnets for modular designs or lids
🟧 5. Assembly Tips by Use Case
| Application | Tips |
|---|---|
| Cosplay Props | Sand edges well; reinforce stress points with epoxy or rods |
| Miniatures | Paint before full assembly; use tweezers for small parts |
| Functional Parts | Use epoxy or hardware fasteners; avoid over-tightening on plastic |
| Models/Figurines | Attach limbs or accessories after painting for easier access |
🟫 6. Common Mistakes and How to Avoid Them
| Mistake | How to Avoid |
|---|---|
| Paint runs and pooling | Apply thin coats, allow proper drying between layers |
| Glue smears or fogging | Apply glue sparingly and clean immediately if needed |
| Misalignment during assembly | Dry-fit first and use positioning aids (clamps, tape) |
| Skipping primer | Always prime for better adhesion and smoother finish |
🧠 Summary
Painting and assembling your 3D print adds the final polish, turning it into a showpiece, prototype, or usable part. With the right tools, preparation, and patience, you can produce results that rival traditional manufactured products—customized to your vision.
🖌️ Finish your prints with pride—your creativity doesn’t stop at the print bed.
📂 Optional Activities
Assignment:
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Choose a multi-part model (toy, figurine, or case)
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Print and paint each part with primer and base color
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Assemble the model using at least one adhesive or mechanical joint
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Submit a photo gallery and a 1-paragraph reflection
