Heidi Swapp Lightbox Inserts: Hobbies. Complementary icon sets are the perfect addition to your Lightbox collection. Customize your sign with icons for a fun, trendy look. This 3 1/2 x 3 x 1/2 inch package contains twenty unique 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.