Thanks to its metal frame, the Printrbot Simple is a sturdy and reliable 3D printer perfect for rapid prototyping. One downside to this is the lack of traction when it is on solid surfaces, and fast prints can cause a lot of sliding. Without a way to secure the machine, it could interfere with other equipment or fall to cause a range of problems. Tilting is another issue with the Simple, especially if filament is mounted on a spool rack and the X-Axis Upgrade is installed. Adding "Printr Feet" to the frame prevents both of these issues, while also providing more air flow to the motherboard!