Import a mesh, paint on its real UVs, and export a full SurfaceAppearance texture set.
Import a mesh, and this reads its real UV layout straight out of the file so you can paint directly on it - the same idea as Shirt Maker and Pants Maker, except the template comes from your model instead of a fixed Roblox one. Paint all five maps a SurfaceAppearance accepts, judge them against a live lit preview, and export PNGs named for the exact property each one belongs in. Your mesh is read in the browser and never uploaded anywhere.
One mesh at a time. All five maps are a single texture set for a single UV layout, so this works on one model per session. Loading another mesh discards everything you've painted - export first. If your model is several parts, they need to share one UV layout (unwrapped together) for a single SurfaceAppearance to apply to all of them.
Export your model from Blender (or any modeller) as OBJ, FBX, or glTF with UVs and drop it above. STL has no UV data at all, so it can't be painted.
Sets roughness and metalness across the whole mesh to real-world values. A good starting point before painting detail on top.
Perfectly even roughness is what makes a surface read as fake. A little noise is usually the single biggest upgrade.
Painting slightly past a shell's edge is intentional - that padding is what stops seams showing on the model. Fill Island and Gradient stay inside whichever shell you click.
Left-drag to paint directly on the model - whichever tool and map is active on the left still applies here, brush through text. Right-drag to orbit, scroll to zoom. Roughness and metalness only mean anything under light, so judge them here rather than on the flat map. Switch to a single map to check UV placement and seams.