Categories and material mapping

AnansiBuild groups every Revit element into a small set of print categories — Walls, Floors, Glass, Doors, Plumbing, and so on. Each category gets its own color in the preview and its own filament slot in the exported 3MF. This is how multi-color architectural prints work: you assign one color per category, and the printer swaps filament automatically.

This page covers what the categories are, how AnansiBuild decides which one a Revit element belongs to, and how to plan your color scheme.

The category list

AnansiBuild ships with the following print categories, organized by the role they play in a model:

Architecture (the structure of the building)

• Walls
• Floors
• Roofs
• Ceilings
• Columns
• Stairs
• Railings

Glazing and openings (split into glass and frame so you can print clear glazing in transparent filament)

• Doors — solid door bodies
• Door_Glass — glass panels in glazed doors
• Windows_Frames — window frames, mullions, sills, trim
• Windows_Glass — window glazing
• CurtainWalls — curtain wall panels (storefront, etc.)

Structure

• Framing — beams, joists, trusses (structural framing)

MEP (mechanical, electrical, plumbing — separated so you can hide them or print them in accent colors)

• Plumbing
• Mechanical — HVAC ducts, equipment
• Electrical
• Lighting — light fixtures

Interiors

• Furniture
• Casework — built-in cabinetry, millwork
• Appliances — auto-detected by family name keyword match (e.g. Refrigerator, Oven, Dishwasher, Washer). Gets its own AMS slot and palette color, separate from generic Furniture.

Massing

• Masses — Revit conceptual mass elements (OST_Mass). Useful for early-stage study models that haven't been resolved into walls and floors yet.

Site

• Site — site components (fences, paving, planting)
• Topography — terrain meshes

Fallback

• Other — anything that doesn't fit the above (generic models, specialty equipment, miscellaneous)

In the Preview Window, only categories that actually contain elements show up. A residential model won't have Mechanical or CurtainWalls in the toggle list because there's nothing to put there.

How elements get categorized

Each Revit element starts at its built-in category (Walls go to Walls, Floors go to Floors, etc.). For windows and doors specifically, AnansiBuild splits the element into glass and frame parts using material name keywords.

If a face's material name contains any of these terms, that face is routed to the _Glass category for its parent element:

• glass
• glazing
• transparent
• clear

Everything else stays with the parent — the frame, the sash, the sill, the trim. This is automatic. You don't need to do anything special in Revit as long as your glass materials are named with one of those keywords. Most out-of-the-box Revit window/door families already use names like Glass, Glass — Clear, or Glazing.

If your custom families use a non-standard material name for glass (e.g. MyCustomTransparentMaterialv3), the glass will be routed to the parent category (Doors or WindowsFrames) instead of the _Glass category. To fix this, either:

1. Rename the material in Revit to include one of the keywords above, or
2. Edit the family to use a standard glass material.

Appliances

Appliances are split out from generic Furniture using family name keywords. If an element's family name contains any of these terms, it gets routed to the Appliances category and its own AMS slot:

refrigerator, fridge, oven, range, stove, dishwasher, washer, dryer, microwave, or the generic substring appliance

This means you can assign appliances to a steel-finish filament without dragging in your dining chairs and lamps with them.

If your appliance family is named something non-obvious (e.g. KitchenUnit_03), it'll fall back to Furniture. Either rename the family or use the right-click reassignment described below.

Reassigning mis-routed elements (right-click)

In the Categories card of the Preview Window, every category is a tree node you can expand to see the Revit families inside. Right-click any family to open a context menu that lets you move it to a different print category — including custom categories you've created with the + New button at the top of the card.

This is the manual override for cases where the automatic routing doesn't match your intent. Common uses:

• A custom planter family that arrives in Furniture but belongs in Site
• A "Generic Models" bucket that needs to be split into multiple print categories
• Specialty equipment that should print in its own AMS slot

Multi-select shortcut. If you check several family checkboxes first and then right-click any one of them, the context menu offers "Move N families to:" instead of just the single-family version. Useful when you have a dozen families that all need to go to the same target category — pick them all, right-click, move once.

Reassignments only apply to the current export — they're not written back to your Revit project. If you want the change to stick, edit the family or its built-in category in Revit.

Creating a custom category (the "+ New" workflow)

Sometimes the 24 built-in categories don't cover what you need. Maybe you're printing a presentation model where the sculptures, signage, and exhibition cases need their own filament color, separate from generic Furniture. Walk-through:

1. Click "+ New" at the top of the Categories card. A small dialog appears asking for a name.
2. Type a name like "Custom Models" or "Display Cases" and confirm. The new category appears in the Categories tree with a default color (assigned automatically) and zero element count.
3. Right-click each family that should belong to the new category and choose Move to → Custom Models. The family moves; its element count transfers; the original category's count drops by the same number.
4. Toggle the new category on or off like any other. It exports with its own AMS slot (overflow slot 16, shared with Appliances and Masses if those are also active — see "The canonical slot mapping" above).

Custom categories live for the current export only — close the Preview Window and they're gone. If you want a custom category to persist, add it back next time (or wait for export presets, which are on the roadmap).

What goes into "Other"?

The Other category is a fallback bucket for Revit elements that don't match any of the mapped built-in categories. In practice that's:

• Generic Models that aren't routed elsewhere by the appliance keyword logic
• Specialty Equipment (Revit's OST_SpecialityEquipment)
• Site components that don't fall under Site or Topography
• Anything else that doesn't have a dedicated print category

If "Other" has a high element count and you care about those elements, expand the tree, see which families landed there, and use right-click → Move to reassign them to a category that prints with the right color. Or create a custom category for them.

Categories you expected but don't see in the panel

The Categories tree only shows categories that have at least one element visible in the active Revit 3D view. If you toggled Site, MEP, or Topography off in Revit's view filter, those categories won't appear in the AnansiBuild preview at all — there's nothing to extract.

To get them back: in Revit, unhide the relevant categories in your active 3D view (Visibility/Graphics, or the Reveal Hidden Elements lightbulb toggle), then re-run Export 3MF. The hidden categories will show up.

This is also why your Categories list might look shorter than the 24-category total: AnansiBuild only shows what's actually in front of it.

Colors in the viewport

Each category has a default color in the 3D preview, designed to be architect-friendly:

| Category | Color | Notes | |---|---|---| | Walls | Light gray | Neutral, lets accents pop | | Floors | Warm tan | Reads as floor without screaming | | Roofs | Mid-gray | Distinct from walls | | Ceilings | Off-white | Subtle | | Doors | Wood brown | Reads as door | | Doors / Windows glass | Translucent blue | Semi-transparent, like real glazing | | Windows frames | Dark gray | Visible against walls | | Curtain walls | Medium-dark gray | Reads as a frame, not as glass | | Stairs | Medium gray | | | Railings | Dark gray | | | Columns | Mid-gray | | | Framing | Brown-gray | Structural feel | | Furniture | Peru / wood-brown | Warm accent | | Casework | Tan | Wood-like | | Appliances | Stainless / cool gray | Reads as appliance | | Masses | Translucent purple-blue | Reads as conceptual / un-resolved geometry | | Plumbing | Steel blue | Reads as plumbing | | Mechanical | Copper | Distinct from plumbing and from Furniture | | Electrical | Yellow-gold | Conventional electrical color | | Lighting | Bright yellow | Light-bulb yellow | | Site | Olive green | | | Topography | Dark olive green | Earthier, distinct from Site | | Other | Neutral gray | |

These colors are written into the 3MF as basematerials, so when you open the file in Bambu Studio, each category arrives pre-colored. You can override any of them in the slicer.

How AMS slot mapping works

If you have a Bambu Lab printer with the AMS (Automatic Material System), the multi-color magic happens automatically. AnansiBuild assigns each category a stable AMS slot number in the 3MF — meaning Walls always go to the same slot, Floors always go to the same slot, and so on across all your projects.

The canonical slot mapping

Here's exactly which category lands in which AMS slot. This is fixed in the code — it doesn't change per project.

| Slot | Category | Slot | Category | |---|---|---|---| | 1 | Walls | 9 | Stairs | | 2 | Floors | 10 | Railings | | 3 | Roofs | 11 | Framing | | 4 | Ceilings | 12 | Casework | | 5 | Doors | 13 | DoorGlass | | 6 | WindowsFrames | 14 | Windows_Glass | | 7 | CurtainWalls | 15 | Furniture | | 8 | Columns | 16 | Appliances + Masses + overflow |

Slot 16 is shared. Appliances, Masses, and any overflow categories beyond slot 15 all map to slot 16. If your project uses both Appliances and Masses (rare in production work, common in early studies), they print in the same filament. To get them on different slots, currently you'd need to manually reassign one of them in Bambu Studio after import.

How to set it up in Bambu Studio

1. Open the 3MF. The slicer reads the slot assignments and shows them in the object panel.
2. Match each AMS slot to a physical filament you've loaded into the AMS.
3. Slice and print. The printer swaps filament automatically at category boundaries.

The slot assignments are stable across exports, so you can build a personal "house style" — for example, "slot 1 is always white walls, slot 2 is always tan floors, slot 14 is always clear PETG for glass" — and reuse it across every project. Save your AMS slot ↔ filament mapping as a Bambu Studio preset and load it whenever you import a new AnansiBuild export.

Multi-color strategies

A few proven recipes for different goals:

Two-color: presentation models

Fastest and cheapest. Almost no filament swaps.

• Color 1 (primary, e.g. white) → Walls, Floors, Roofs, Columns, Stairs, Ceilings
• Color 2 (accent, e.g. dark gray) → Doors, Windows_Frames, Railings, CurtainWalls
• Glass → skip or use Color 1

Works well for early-stage massing and study models.

Three-color: architectural with clear glass

The classic architectural model look.

• Color 1 (white) → Walls, Columns, Structure
• Color 2 (gray) → Floors, Roofs, Site, Topography
• Color 3 (clear PETG) → WindowsGlass, DoorGlass, CurtainWalls
• Windows_Frames → Color 2

The clear PETG for glazing is the move that makes the model read as a real building. Print walls in 0.2 mm layer height; glass in 0.12 mm for transparency.

Four-color: detailed presentation

For competitions, exhibitions, final reviews.

• Color 1 (white) → Walls, Ceilings
• Color 2 (dark gray) → Floors, Roofs, Site
• Color 3 (clear) → WindowsGlass, DoorGlass
• Color 4 (black) → Windows_Frames, Doors, Railings, CurtainWalls

Furniture, plumbing, and other secondary categories get folded into the four colors based on what reads best for that project.

Zoned / diagrammatic

For program diagrams, phasing studies, or thermal/circulation analysis. This one needs setup work in Revit.

• Create separate Revit walls (or duplicate categories) for each zone — Public, Private, Service.
• Assign different materials to each zone group.
• Map each material to a different AMS slot post-export in Bambu Studio.

Practical tips

• Default to "all on" then trim. Easier to toggle a few categories off than to figure out what's missing.
• Hide MEP for presentation models. Unless you specifically want to show ductwork, MEP categories add print time and complexity for marginal aesthetic value.
• Topography is its own animal. It's slow to print at large scales. Consider exporting it separately at a coarser detail level, or skipping it and printing on a wood base.
• Test glass first. Clear filament is finicky. Print a small window pane on its own before committing to a full-building print.
• Section box your model first. A model cropped to one floor or one wing exports faster, previews faster, and prints faster than a whole-building export with categories toggled off.

Where to next

• Workflow basics: Getting started
• Splitting a too-big model: Cuts and slicing
• Picking the right scale for the printed result: Printers and scales
• Glass not separating from frames? → Troubleshooting