This is a fully 3D printed Hand Grip Strengthener. While in microgravity, the muscles in an astronaut’s body tend to relax for long periods of time, including those in the hand. A journey to mars would likely include months in microgravity, and with this hand grip strengthener, astronauts can exercise those muscles even while performing activities outside of their scheduled exercise times. It prints as a support-free, three-part assembly, and fits on a 6x6x6 inch cubic build platform. In the future, the design could be customized so that different amounts of force are necessary for full compression. Five 3D printed compression springs are equidistant from each other in the rectangular body, and a viewing window makes it easy to tell when the springs are fully compressed. The completed assembly fits well in the hand at default size, but because it is completely printable it is also completely scalable, and size can be adjusted for any astronaut.