I was inspired to make this by UPWDesign's Caliburn Spring Quick Swap Butt https://www.thingiverse.com/thing:2599487 and took his concept and applied my own take on it to the TCU. It replaces the TCOGEndCap.stl and allows you to quickly remove and replace your spring without disassembling the blaster and without any tools or additional hardware. Makes it easy to swap springs between rounds of PvP with different FPS caps or remove your spring for long term storage.

Warning: I haven't done any testing with high spring loads like K25 or K26. I play HvZ which has low FPS caps so have only used K31 and 788 in mine. It should be fine if you print it with the same settings as me as the weakest load bearing part would be 1.2 mm thick and solid plastic. I just can't make any guarantees. If you print one and use it with stronger springs, please let me know how it goes. (it is perfectly fine, i noticed x part was getting fatigued, it exploded into a million pieces when primed, etc.)