Heidi Swapp Lightbox Inserts Party Icons. The perfect addition to the Heidi Swapp Battery Operated Lightbox (sold separately). Customize your sign with mini icons for a fun, trendy look. This package contains twenty unique 3 x 3 inch lightbox inserts.WARNING This product contains chemicals known to the State of California to cause cancer, birth defects or other reproductive harm. Do not mouth or chew. Imported.