Swatches prevent your 3D editor's export process from removing materials you want to upload, but haven't used on the model.
Chances are, you'll have many more materials than meshes, and most 3D applications will automatically remove unused materials when exporting. To ensure your GLTF file includes all the materials you have tagged, we create ‘swatches’ for each material in the file.
A swatch is just a tiny mesh you tag with V[SWATCH], then apply a material to, guaranteeing the material is then available to generate variants. Swatches won't be tagged with anything else (like a tag-name), as they are just a delivery method for your tagged materials.
We recommend you use single polys or planes for swatches, so as not to bloat the file-size.
Swatches are always removed before generating product variants, so cannot be seen in the final output and don't contribute to the end-user's download size.
Don’t place swatches very far away from the origin, as this may change the origin or bounds of the model in AR when they are automatically calculated. The best position is usually floor level at the origin, scaled down so they don't get in the way of editing the main model.