How to Prepare Your 3D Model for Printing

A digital horse sculpture in the modelling workspace. The model defines the form; scale, geometry and production requirements still need checking before manufacture.

Before sending a model for printing, check that the file describes the object you actually want to receive. A good render can hide an incorrect scale, a paper-thin surface or a connection that has no room to fit.

You do not need to become a production technician before making an enquiry. A few checks, together with a clear account of how the object will be used, make the conversation more useful. This guide is for projects with an existing model. If you are starting with sketches or photographs, design development comes first.

Establish the finished size

Write down the intended overall dimensions and units, even if they are already set in your modelling software. Identify any measurements that must remain fixed, such as the distance between mounting points or the opening for an existing component.

“Print at the file size” is less helpful than a dimension that can be checked. If you are producing a scale model, state both the scale and one expected physical measurement. This gives the studio a way to identify a mismatch before production.

Treat resizing as a design change, not just a way to adjust the overall height. Reducing a model also reduces its walls, lettering and connection features. A delicate detail that worked on a larger version may need to be redesigned at the smaller size.

Check that the geometry describes a physical object

A printable mesh should define the intended volume without accidental gaps, conflicting faces or unwanted internal surfaces. This is often described as watertight or manifold geometry. It does not mean a printed vessel is automatically liquid-tight.

An intentional opening, such as the mouth of a vase, is different from a missing face in its wall. The model still needs to describe the wall thickness and the surfaces around that opening.

If software reports a geometry error, do not simply dismiss it because the object looks complete. Compare the repaired result with the original. An automatic repair is only useful if it preserves the shape you intended to make.

Separate wall thickness from small detail

A wall, a raised letter and a long projecting stem are different manufacturing problems. Identify each in the brief instead of asking for one minimum thickness to cover the entire object.

Suitable dimensions depend on the printing process, material, geometry and handling requirements. Manufacturer limits are specific to the conditions tested; they should not become universal rules for every project.

For example, imagine a miniature architectural screen with fine vertical members. The design question is not only whether those members can appear in a print. They also need to survive the handling expected during assembly and presentation. Flag the intended use, and identify which details can be adjusted without changing the design's character.

Explain what needs to fit

If two parts connect, show the relationship between them. Include both files where possible and identify any purchased component that the print must accommodate.

Clearance is the intended space between mating features. Dimensional tolerance describes the permitted variation in a dimension. Neither can be replaced by a single universal number for all printed assemblies.

Describe the desired behaviour: should the parts slide, rotate, locate once, or remain permanently joined? A drawing with the critical dimensions marked is more useful than a message saying the fit should be “tight”. Where the fit is important, discuss a test piece before committing to the full set.

Mark the surfaces that matter

Tell the studio which face will be seen, photographed or touched. Also identify areas that must remain accessible for assembly. These priorities help inform orientation and support decisions.

You do not have to supply a finished support layout. A simple annotated view can communicate where marks would be especially distracting and where a joint might be acceptable. If the object will be viewed from every side, say so rather than assuming there is a hidden back.

For larger or complicated forms, discuss whether separate components are appropriate. Agree the final appearance of the joins as well as who will complete the assembly. Dividing a model is not a reason to leave those decisions until after printing.

Export a version that can be checked

Keep the editable original and identify the exported file clearly. Include a version number or date, and state which file should be used if you are sending alternatives.

Check that curved surfaces still have the intended shape in the export. A smooth-looking viewport can conceal a coarse mesh. More polygons are not automatically helpful, but an export should not introduce visible facets that were not part of the design.

STL, OBJ, STEP and 3MF serve different purposes and carry different information. Tell us which formats you have rather than repeatedly converting a file and assuming that conversion repairs it. File requirements can be confirmed for the proposed production route.

Send a short production brief with the model

Include the intended size, quantity, use, finish and deadline. Highlight critical dimensions, delicate features and any parts that connect to other objects. Say whether the model is final, needs repair or is still being developed.

Keep reference images separate from the production file and explain what they illustrate. A colour reference should not be mistaken for a request to reproduce another object's shape.

LILIS LAB can assess design support and production as separate stages. If further modelling is required, that work should be agreed before treating the file as approved for manufacture. An accurate final production quotation follows assessment of the completed, approved model.

HAVE A FILE THAT NEEDS A SECOND LOOK?

Send the model, its intended dimensions and a short explanation of what it needs to do.
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