These are (very) primitive jigs to help in disassembly of the FAS 604 air pistol, typically to repair seals.
FAS 604 Jig v2.stl - This makes it easier to knock out the pin.
FAS 604 Valve Puller v1.stl - Print two of these and use them together (top + bottom) to pull the valve.
The FAS 604 is a hand cocked pneumatic air pistol, shooting a .177 caliber pellet, typically at 10 m targets.
Please note: These might also work with the FAS 6004, but I do not have one to test.
The author hasn't provided the model origin yet.