The Katz-Moses sharpening guide from kmtools.com is more than a bit fiddly to align properly without dropping your chisel a dozen times during the process, so I designed a jig to hold everything steady and get you close to the two most common angles for sharpening. It also provides a nice surface for squaring a blade against the front of the guide, which is a lot easier to do than their recommendation of using a square on the back of the jig (which only works for plane irons, anyway).

Models are available for both 25° and 30° in both right and left handed versions (the files are named for which size the jig sits on, so use the opposite hand – photo showing my left hand using the “right” model), along with 29° and 31° for Rob Cosman fans.  Hit me up if you want a custom angle or a larger wall (e.g. for a thick mortise chisel).

You can find CAD source for this model at Onshape.