How to assemble a model printed in several 3D parts

This guide mainly covers decorative models printed in filament, especially PLA or PETG. It is not a validation method for load-bearing or safety parts.

Hold the parts against each other without glue. Check their orientation, the insertion of the tenons and the alignment of the visible surfaces.

Do not only check each pair of parts: also try their position in the whole model. This lets you plan an assembly order without blocking the insertion of a later part.

Remove leftover supports and the small burrs that get in the way of contact. If needed, sand the area lightly, without rounding the edges or changing the fit of the tenons.

The surfaces must be clean and suited to the chosen glue. Remove dust and grease marks, then let dry after cleaning. Follow the manufacturer’s recommendations for preparing the plastic.

For a small decorative assembly in PLA, a compatible cyanoacrylate glue may do. For a large surface to align, choose a glue with enough working time; some two-part epoxies allow it.

With PETG, do not assume that a glue that works well on PLA will give the same result. Check its compatibility and test it on two offcuts printed with the same filament.

Prepare the protective equipment listed in the safety data sheet and work in a properly ventilated space.

Prepare the holding before applying the glue: masking tape, small clamps with protected jaws or a support shaped to the part. First check that this setup does not mark the surfaces.

Apply the recommended amount of glue, join the parts and check the seam from several sides. For an epoxy, also respect the prescribed proportions and mixing.

Hold the alignment without crushing a thin wall. If you have to force to close the joint, go back to the dry fit rather than tightening further.

On a model made of many pieces, prepare groups that are easy to handle. For a statue, for instance, you can treat the base, the body and the accessories separately when the geometry allows it.

Keep fragile details aside as long as they might get in the way of handling. Before each gluing, check that the surfaces needed for the next step remain accessible.

Keep your reference marks until the end of the assembly. A photo of the dry fit can serve as a reference.

A glue that has started to set has not necessarily reached its final strength. Respect the holding time and the full curing time given for the product.

During this wait, support overhanging parts rather than letting their weight pull on a fresh joint. Only start sanding the seams once the glue has cured enough according to the instructions.

Check the whole model without glue first. Then prepare the surfaces, glue in stages and let cure before handling or finishing the model. Fit and assembly order are settled before gluing, not during.