The MS-2000/MS-2000M military strobe light is sometimes found with a broken or missing switch - this model is designed to replace it. The strobe uses a magnetic switch to enhance its' weather resistance during field use.

Other than the printed model, you require:

1. One 10x4x2 rare earth magnet, which is pressed into the cavity on the sliding switch part.
2. The original switch spring (typically still found with damaged MS-2000 units) or a piece of thin metal cut and bent to replace it. 
3. Potentially a dab of superglue to secure the magnet into the sliding switch portion of the print, though it should friction fit. Tolerances may vary based on your particular magnet and print settings, though.

Both parts should slide right in and are kept captive by the battery cover as seen in the photos. Luckily, should you lose them when replacing the battery, they are extremely quick to print and use very little filament.

Happy strobing!