This case is made to hold 12 small needle types files. I was not satisfied with the plastic bag that my set came in so I made this case.

You may desire to scale the cap up slightly for an easier fit; or sand the corners slightly and it should be a tight fit. The holes come out to approximately 0.25" diameter. I've provided CAD files in case you desire to re-size holes; or simply scale the entire model to fit your need.