3D architectural model: scale, export and splitting

A 3D-printed architectural model is won or lost before printing. The scale, the wall thickness and the cleanliness of the export decide what you get, far more than the machine. A model built for the screen is not necessarily a model that can be made.

This article is deliberately technical. For an overview of the profession (deliverables, project phases, confidentiality), start with our guide to 3D printing for architects. Here we detail the choices that make a good 3D architectural model: scale, fineness, export, splitting and limits.

Choosing the scale: what it implies

Scale does not only set the size. It sets the level of legible detail and the number of parts to assemble. Our FDM printers produce parts up to 256 mm per axis: anything larger is split into modules.

Scale	1 mm on the model	Typical use	Legible detail
1:500	50 cm real	District, site, masterplan	Volumes, massing, topography
1:200	20 cm real	Block, single building	Massing, window grid
1:100	10 cm real	Competition model	Openings, balconies, setbacks
1:50	5 cm real	Façade, construction detail	Railings, slab edges, simple joinery

Two benchmarks:

• A 60 m long building is 12 cm at 1:500, 30 cm at 1:200 and 60 cm at 1:100. At 1:200 it already exceeds one build plate: it will be two modules.
• The larger the scale, the longer the print time and the more modules. A site model at 1:200 can need six times more parts than the same footprint at 1:500.

Ask what the message is: a massing model gains nothing by going from 1:500 to 1:200. A façade presentation model loses legibility below 1:100.

Minimum fineness: the 0.8 mm rule

In FDM, plastic is laid down in strands. Below about 0.8 mm thick, a wall prints poorly: fragile, uneven, sometimes missing. This value applies on the model, not in the real world, so you need to convert.

Real thickness represented by 0.8 mm:

• at 1:500: 40 cm
• at 1:200: 16 cm
• at 1:100: 8 cm
• at 1:50: 4 cm

In practice. A 20 cm wall, perfectly printable at 1:100 (2 mm), becomes too thin at 1:500 (0.4 mm): it is thickened to 0.8 mm, so visibly oversized. Window mullions at 1:500, open railings and thin sunshades do not print. They are thickened, simplified or removed, with your agreement, before printing.

Remember: at block or district scale, think in volumes, not elements. What the eye cannot distinguish at one metre does not need to be in the file.

Preparing the export from your software

The number one cause of delayed models is a file that is not watertight. A manufacturing mesh must be closed (no holes), with volumes that have real thickness. A façade modelled as a single surface, perfect on screen, has no volume to print. For the general rules, see our article on preparing an STL file.

Checks that apply whatever the tool:

1. Give every surface a thickness. Roofs, curtain walls, parapets: each element must be a solid, not a plane.
2. Remove what cannot be seen at scale. Interior furniture, detailed frames, plants, labels, dimensions. A lighter model exports faster and prints better.
3. Merge volumes that touch. Two overlapping solids create stray internal faces.
4. Check normal orientation and the absence of duplicate faces.
5. Export as STL, OBJ or 3MF at 1:1 scale, stating the unit (metre, millimetre). We apply the model scale.

Depending on your software:

• SketchUp: work with closed groups and components. A solid inspector extension finds open edges. Avoid zero-thickness faces.
• Rhino: turn surfaces into closed polysurfaces, check with the ShowEdges command that no naked edges remain, then export as a mesh.
• Revit and ArchiCAD: these tools produce rich but heavy models. Export the 3D view of the volume you want, turn off unneeded categories (furniture, equipment) and send what your version can export. If the format is not standard, tell us: we will say whether the file is usable or what to adjust.

When in doubt, send us the file as it is. We review it before quoting and list the corrections needed.

Splitting large models into modules

Beyond 25 cm, the model is split into modules. The split is not a detail: it shapes the final reading.

• Follow the lines of the project. A cut along a street, a façade joint or a plot boundary stays invisible. A cut through the middle of a volume shows.
• Plan assembly marks. Pegs, notches or grooves prevent misalignment on assembly.
• Think about removable levels. To show the interior, the model can separate by floor. Plan it before the export, not after.
• Anticipate transport. Plate-sized modules are easy to handle and ship; an assembled 80 cm model, much less so.

A 1 m by 60 cm site model typically means around ten modules. Tell us the footprint and the scale: we propose the split and you validate it.

The finish: why matte PLA

For an architectural model we recommend matte PLA, white or tinted. It reduces the visibility of layers, does not reflect light and gives the monochrome look expected of a model. PLA is also permanently in stock: it does not extend lead time.

Print layers remain slightly visible up close, especially on sloped surfaces and pitched roofs. This is a feature of the process, not a defect. If that look bothers you for a competition submission, tell us when you ask.

What 3D printing does not do

For transparency, here is what we do not offer in-house:

• Transparent glazing. A clear panel is cut separately. We plan the recesses to receive it.
• Vegetation. Trees and foliage call for other materials. A simplified volume is possible, realistic foliage is not.
• The wooden base. We print the built form, not the joinery.
• Details below 0.8 mm at scale, as seen above.

For mixed models, the printed structure combines well with elements you add: glazing, vegetation, base. We help you plan the locations.

Start your model

Based in Lille or the metropolitan area? Our page on architectural models in Lille details the local offer: pickup by appointment, delivery included in the metropolitan area, standard lead time of 5 to 7 working days.

For an agency or a recurring order, start a professional estimate with the scale, footprint and deadline. We reply with a proposed split and a lead time.

Frequently asked questions

Which scale for a competition model?

1:200 or 1:100 are the most common. 1:200 suits a building in its immediate context, 1:100 lets you read openings and balconies. Beyond that, the number of modules and the print time rise quickly.

What is the minimum wall thickness on the model?

About 0.8 mm on the model. At 1:100 that is 8 cm real: a 20 cm wall passes without trouble. At 1:500, 0.8 mm represents 40 cm: a thinner wall is thickened.

Can I send a Revit or ArchiCAD file directly?

It is better to export a mesh (STL, OBJ or 3MF) from the 3D view, turning off unneeded furniture and equipment. If your software cannot, send what it exports: we will tell you whether the file is usable.

What if my model is not watertight?

We flag it before quoting and list the corrections. For simple defects we handle them. For a model that must be rebuilt, we propose a separate quote.

Can you print glazing and vegetation?

No. We print the structure and the built form. Transparent glazing, vegetation and the wooden base are added separately; we plan the recesses in the model.

How long does a model take?

The standard lead time is 5 to 7 working days, depending on scale and number of modules. A shorter time is possible on request. For pricing, use the estimate.