Why the designer rejects your design (and how to fix it)
It's almost always one of four things: the file isn't PNG, JPG or SVG, it's over 8 MB, the image has no clear shape, or it has too much detail. Thicken the lines, clean the background and simplify: then it goes through.
What the designer checks before giving you the piece
The designer doesn't look at your image like a photo: it looks for a dark shape on a light background and traces its outline. That outline is what later gets raised into 3D. If the shape doesn't stand out from the background, there's no outline to trace and the process stops right there.
Then it cleans up the trace: in almost every product, specks that don't touch the drawing and measure less than 1.5 mm at the chosen size are removed automatically, because they couldn't be printed. A notice tells you, but nothing stops.
Finally it builds the piece in your browser. The trace is simplified down to a maximum of 6,000 detail nodes (fewer on devices with little memory), and if the drawing still doesn't fit in the available memory, generation stops so you don't get a badly made piece.
Check the file format and size
The designer accepts PNG, JPG and SVG, up to 8 MB. iPhone photos in HEIC, WEBP files and PDFs won't go through: open them in any editor and save them as PNG or JPG.
If the photo is over 8 MB, crop it to the area of the drawing or export it at a lower resolution. The designer works with the image at 1,024 px on its longest side, so a huge photo doesn't add any more detail.
Leave a single shape with good contrast
The ideal is a dark drawing on a white background: a plain background is removed automatically. If it's a photo or a logo with a colored background, use “Clean background with AI” (1 credit, PNG or JPG only) or “Clean background” inside “Edit image”.
If the drawing is light on a dark background, or the lines get lost, invert the colors or raise the contrast in a photo editor before uploading, or go over the drawing with “Brush” and “Eraser” in “Edit image”. A transparent PNG with a light drawing gets inverted automatically.
Thicken thin lines
A pencil line looks fine on screen but can't be printed. In “Edit image”, with PNG or JPG, the “Reinforcement intensity” thickens the outer outline of the shape; the lines inside don't change: go over them thicker with the “Brush” or in the original drawing.
On stamps, “Thicken thin lines” is on by default: lines under 0.5 mm are brought up to the printable minimum automatically. If you turn it off and there are thin lines, a warning shows up.
Lower the detail if generation stops
If you see “This drawing has too much detail”, the design is too heavy for your browser's memory. Simplify the image: erase fill and texture with the “Eraser” in “Edit image” or in the original, and upload it again.
Below the image you'll see the “Traced · N nodes” counter: the simpler the image, the lower the number. For reference, the designer works with up to 6,000 nodes, and fewer on devices with little memory.
Match the size to the detail you want to keep
In almost every product, loose parts under 1.5 mm are removed during cleanup. If a part you care about disappears, make the piece bigger with “Overall size” (you type it in the field, from 30 to 1000 mm) or connect that part to the rest of the drawing.
The same happens with the Stencil: if the design is too detailed for its size, the sheet comes out blank and the designer warns you. Make the shape bigger or simplify the drawing.