In working with my students with the VEX IQ Robotics kits, I identified several batteries that would not properly eject from the robot brain. After identifying the problem, I designed and 3D printed a tool that ejects stuck batteries with almost no effort.
The 100 micron layer height is not absolutely necessary, but I chose to print at that setting because of the thin slope on the prongs. I also set my print up to include 4 outlines. In PLA this has proven to be incredibly strong.