Your personal hand trainer
Designed to be fully 3d printable with no additional hardware.
Classic design and 3 variants of the spring (Hard, Medium and Light, marked with a letter), fully swappable.
With rightly calibrated filament you should be able to just fit everything together snuggly.
Regular PLA is slightly slippery, handles printed with matte PLA should be good, but i also give you access to Super Comfordable Fuzzy Skin Handles, you need to try them out, really really.
Remember to print springs and clips from PETG to give them some durability (if you want to impress your friends you can print them from PLA and just destroy them with your massive muscles, ladies love it)