I created my miniature gym. Where my main tools were Autodesk 123D Design and Fusion 360, which helped me to craft the exact copies of different types of barbells and dumbells.
https://youtu.be/8EPC99gWua0

I present to your attention a rack for dumbbells. You can download other gym equipment here:
https://www.instructables.com/id/3d-Printed-Tiny-Gym/