3Doodler Start plastics are low-heat, BPA-Free and Non-Toxic so they completely safe for kids and are compatible with 3Doodler Start Pen only. Bring any idea to life or personalize your existing items. Safe to Doodle on almost any material, such as LEGO, and the plastic can be easily removed, though will adhere firmly to clear plastics. 3Doodler Start Plastics extrude to 6 times the original length, so one 6-inch strand gives over 35 inches of doodling.