Hi,  I think that the easiest way to produce a few of these
26 tooth sprockets would be to laser cut them.  Anyone familiar
with a program like Corel Draw could knock out the file in about 15
minutes.  (I have found that doing it once or twice a year requires
me to re-learning the process each time.)

The hub would be a simple job on a machine lathe; make a shoulder on
the hub and a matching center hole on the gear.  I have yet to see
a printed part that matches the finish on a laser cut or machined part.
You can always see the surface texture of either the process or the
material.

Scanning would be a waste of time and money on a part like this --
with its simple geometry.  And after it's scanned, you'll spend
considerable time touching up the file.  I'll bet that the steam
engine burner shown on Jay's Garage cost him at least $1000.

The flat gear blank for your 26 tooth gear would take less than a
minute to cut on an industrial laser.

The real problem is finding a place that will sign on to do your short
run job without a significant set up charge.

Regards,
Craig Smith