Introducing the next release in my RC Crawler Modular Courses, Realistic Rock Obstacles. Test out your crawling skills or challenge your friends with these 3D printed obstacles. Four different size rocks to test out your rigs capabilities while staying indoors. Each rock has small rubber feet to add grip to smooth surfaces like tile and wood flooring. They also have holes in the bottom with rubber caps that can be filled with various things to add more weight for stability. Note: do not fill with liquids More obstacles will be offered in the future. Parts are printed with plastic and designed for indoor use. They are not made to be left outdoors. Rocks may have small imperfections due to the 3D printing process but will have no affect on usability. Designs may change slightly in order to continuously improve the obstacles for both strength and usability.