Kid on Board sign – free two-colour STL

Everything prints flat, face up. On a single-colour printer, add a filament change (colour change) in your slicer at the height shown under the preview – that is the base thickness. On an AMS, MMU or tool changer, download the ZIP and load the base and top STLs together as one object (they share the same coordinates), with a filament for each; or download the Colour 3MF, which opens in Bambu Studio and OrcaSlicer with both parts already on their own filaments.

Bold, high-contrast drawings: a black logo or silhouette on a white or transparent background. PNG with transparency and SVG work best. Use Threshold to decide what counts as dark, Invert for a light drawing on a dark background, Smoothing to round off jagged pixels and Detail to keep or drop small specks. Photos do not trace well – use the Lithophane Maker for photos.

The common clear suction cups with a mushroom-shaped head (about 8–9 mm) and a thin neck (about 4–5 mm) fit it: push the head through the round entry, then let the sign hang so the neck drops into the narrow slot above it. Measure your suction cup and set the head and neck sizes to match.

Only on steel panels such as most boot lids, doors and tailgates – not on plastic bumpers, aluminium panels or glass. The pockets are on the back and open at the bed, so you press disc magnets in after printing (a drop of glue keeps them in). Use strong neodymium magnets, and take magnetic signs off before motorway driving or a car wash.

PETG or ASA. A car in the sun gets far hotter than PLA can take (PLA softens around 55–60 °C), so a PLA sign behind a windscreen or rear window can warp. PLA is fine for pet tags, indoor signs and badges.

Instead of a rectangle, circle or other fixed shape, the base follows the outline of your artwork and text, grown by the offset you set – like a sticker with a border. If the parts are far apart and the outline breaks into pieces, increase the offset.

The 3D Stamp Generator makes mirrored rubber-stamp style blocks, and the Stencil Generator cuts the image out as holes for spray painting. The 3D Sign Generator makes text-only desk, door and wall signs. This maker is for flat two-colour pieces that combine a traced image with text on a shaped base – car signs, badges, plaques and tags – with hanging holes, a suction-cup keyhole or magnet pockets.