Assembly Tips
Everything you need to know about joining your 3D printed parts — glue types, prep tips, and techniques for FDM and resin prints.
Take your time with assembly. Most mistakes happen by rushing. Clean surfaces, correct adhesive, and a little patience make the difference between a great result and a frustrating one.
Surface Preparation
Good adhesion starts before the glue. Spend a few minutes preparing your surfaces and you’ll get a significantly stronger bond.
🖨️ FDM Prints
- Sand surfaces lightly with 220-grit sandpaper. Rougher surfaces bond better than smooth ones.
- Wipe with isopropyl alcohol (IPA) to remove dust and oils from your hands.
- Remove any support material stubs and make sure faces are flat before joining.
- Dry-fit parts before gluing and adjust the fit if needed.
🧪 Resin Prints
- Sand surfaces lightly with 400-grit sandpaper since resin bonds best with a little texture.
- Wipe with isopropyl alcohol or acetone and let dry fully before applying adhesive.
- Resin parts are very precise, so dry-fit first to check alignment before committing to glue.
- For small delicate joins like weapon handles or wings, use a thin layer of superglue for a clean bond. If you have superglue activator, it will help ensure an instant bond between parts.
- Work only on hidden faces when sanding to avoid scratching visible surfaces.
Choosing the Right Adhesive
The wrong glue can weaken joints or damage prints. Here’s what to use and when.
Cyanoacrylate (Super Glue)
The go-to for most 3D prints. Fast-setting, strong, and works on almost all plastics. Use a thin layer of superglue for tight-fitting parts and a thicker layer to fill in any gaps. Activator spray speeds cure time, but is not a necessity.
Plastic Weld / Solvent Cement
Works by chemically melting the plastic surfaces together by creating a molecular bond rather than surface adhesion. Excellent for PLA, ABS, and PETG. Apply sparingly, hold for 30 seconds.
UV Resin (as glue)
Apply a small amount of liquid UV resin to the joint, position parts, then cure with a UV torch. Creates an exceptionally strong same-material bond for resin parts.
Two-Part Epoxy
Mix equal parts resin and hardener. Slower cure (5–30 min depending on type) but extremely strong and gap-filling. Great for larger parts or joints that need extra strength. Can be shaped before curing.
Hot Glue
Quick and easy but not for detailed work as it can warp thin FDM parts with heat. Good for low-stress joins on larger, thick-walled pieces. Not recommended for fine detail or resin.
Gorilla Glue (Polyurethane)
Expands as it cures, so it is useful for gap-filling on large parts. Dampen one surface before applying. Note: expansion can push parts apart if not clamped, and squeeze-out can be messy.
Avoid PVA / white craft glue on 3D prints as it doesn’t bond well to plastic surfaces and will fail under any load. It’s also water-soluble, so humidity will weaken it further.
Assembly Tips & Techniques
Always dry-fit first
Before applying any adhesive, assemble the whole model dry. Check alignment, identify any parts that need trimming, and plan the assembly order so you’re not rushing once glue is applied.
Work in sections
Glue smaller sub-assemblies first, let them cure fully, then join them together. Trying to assemble everything at once leads to misaligned joints and parts that shift while the glue sets.
Use as little glue as possible
More is not better. Excess adhesive squeezes out of joints, creates visible residue, and can cause fogging on resin prints (especially with superglue). Apply a thin, even layer and press firmly.
Hold still for longer than you think
Even “fast” superglue benefits from holding parts firmly for 60 seconds. For epoxy, clamp or support the joint until fully cured. Movement during cure creates weak bonds.
Fill gaps with putty or superglue and baking soda
Small gaps between parts? Apply a thin layer of superglue, then immediately sprinkle a tiny amount of baking soda on top. It reacts instantly, creating a hard, sandable filler. Perfect for seamlines. Milliput or Green Stuff work for larger gaps.
Clean up squeeze-out immediately
For resin prints, wipe excess glue with a dry cloth or acetone-dampened cotton bud before it sets. Dried superglue can be carefully scraped or sanded but it’s much easier to deal with wet. Do not use acetone on FDM prints.
Let it cure fully before priming or painting
Most glues need 24 hours to reach full strength even if they feel dry in minutes. Primer and paint solvents can weaken partially-cured joints. Give everything a full overnight cure before moving to finishing.
Glue Selection at a Glance
🖨️ FDM Prints
- Best all-rounder: Thin superglue
- Strongest bond: Solvent cement or 2-part epoxy
- Gap filling: Thick superglue and baking soda, or epoxy
- Large structural joins: 2-part epoxy
- Quick temporary hold: Hot glue (thick parts only)
🧪 Resin Prints
- Best all-rounder: Thin superglue
- Strongest bond: UV resin or 2-part epoxy
- Fine detail joins: Thin superglue with activator
- Gap filling: UV resin or 2-part epoxy
- Avoid: Solvent cement (won’t work on resin)