The black lines in the SVG in the file are cut lines, the green lines are decorative score and engrave lines to mark the hours; they are optional and can be omitted. Once you cut all the pieces, glue the numbers to the squares, the square for 12 is slightly larger than the rest. Then use a DIY clock kit and thread the central post through the hole in the face, screw on the nut, and attach the hands. This file uses a 5/16" diameter hole, but you can resize it. Then, mount the face and the numbers to the wall; I recommend removable adhesive such as 3M Command Strips.

I've included STL files to make this on a 3d printer as well.

Enjoy!