This is a one way ratchet that at the moment functions in a clockwise direction. To print a second ratchet that can function in the counter-clockwise direction, the ratchet and ratchet gear STLs simply need to be mirrored to create a counter-clockwise ratchet. The gear pin and ratchet cover do not need to be mirrored since they are symmetrical and do not affect the direction of the ratchet. This ratchet is a first build, so keep in mind that everything may not work perfectly like a commercially manufactured ratchet. For the purpose of making tool attachments, the ratchet head is about 12mm x 12mm.
NOTE: The description above has been corrected from my original post. Originally I said that it functions in a counter-clockwise direction, but the STLs are actually designed to create a clockwise ratchet. The images of the ratchet I printed out are of a counter-clockwise ratchet.