ArchAi3D_Qwen_Material_Changer

Kitchen design clients don't want to hear "we'll mock it up." They want to see the countertop in Carrara marble, then in black granite, then in oak - and they want the rest of the kitchen to stay exactly where it is. ArchAi3D_Qwen_Material_Changer is the ArchAi3d Qwen pack's node for exactly that job: 48 material presets across six categories (stone, wood, metal, fabric, paint, tile), aimed at a specific object, with a default preserve_rest toggle that appends the clause "keep everything else identical."

The default custom material is even "white Carrara marble with gray veining" - the author clearly lives in this exact demo loop. Set object_preset (or a custom_object like "the dining room table surface"), pick a material, hit run, and Qwen-Edit redraws that surface. Rinse, repeat, and you've got a client presentation in five minutes.

The inputs that matter

• object_preset / custom_object - what to change: countertop, flooring, wall, backsplash, cabinets, furniture, and 8+ more presets. The default is custom, so be ready to type an object.
• material_category + material_preset - stone/wood/metal/fabric/paint/tile, each with 8 presets (Carrara, black granite, oak hardwood, walnut, stainless, brass, velvet, linen…). Or custom_material for your own spec - the tooltip is right that specificity wins: "dark walnut with rich grain and matte finish" beats "wood."
• preserve_rest - default true, and the whole point. It's the "keep everything else identical" clause, and it's the difference between a material swap and a room redesign.
• scene_context - the scene description. Feeds consistency; worth one sentence.

Outputs: prompt and system_prompt (wire into your Qwen encoder - the system prompt is tuned per material category), plus material_description showing what got applied.

How it works

It's a prompt builder like the pack's camera nodes: material category maps to a per-category system prompt, the object and material descriptions get woven into a "change the [object] material to [material]" instruction, and preserve_rest appends the stability clause. Everything then goes through Qwen-Edit, which regenerates the frame - which is exactly why the stability clause matters: Qwen-Edit is a whole-frame re-emitter, so without it the "marble countertop" instruction can quietly repaint the cabinets too.

Installing it

Ships in ComfyUI-ArchAi3d-Qwen by Amir Ferdos (ArchAi3d):

# ComfyUI Manager: search "ArchAi3d Qwen"
cd ComfyUI/custom_nodes
git clone https://github.com/amir84ferdos/ComfyUI-ArchAi3d-Qwen.git
cd ComfyUI-ArchAi3d-Qwen
pip install -r requirements.txt

Restart. Bring your own Qwen-Image-Edit model (GGUF-quantized in practice) and the pack's encoder. The material list itself is hardcoded presets - no downloads, no extra models.

Common issues

• The swap overflows the object. Qwen-Edit re-emits everything, so "change the countertop" can bleed into nearby surfaces. Keep preserve_rest on and describe the object precisely ("the kitchen island countertop", not "the counter").
• Materials reinterpret, not render. Carrara marble with gray veining is a strong instruction, but the exact veining is the model's call. Iterate on the seed for the look you want.
• Pattern-matching presets. "Tile" as a category and "tile" as a wall covering can get muddled if your object description is loose - name the surface explicitly.

For material exploration workflows - the README literally walks through trying countertop materials back-to-back for a client presentation - this is the pack's killer editing node, and it's the one where the "keep everything else identical" clause pays for the whole install.