Any real-world object or printed material can carry a Spatial Mod. Business cards, brochures, posters, packaging, and product labels all work. If you already have printed materials, you already have a canvas.
Universal Icons tell your audience the material is scan-able before they ever raise their phone. Download the free icon set and print them as stickers for existing materials, or send the image files to your designer or print shop to incorporate them into new designs.