At work we have this cool Canon copier that is also a printer. It has a duplex widget that allows one to print on both sides of a sheet of paper. Of course this is fairly niche enough for Apple to have not supplied drivers explicitly for it, but the ‘generic Postscript’ driver does work well enough to print, just not duplex.
And of course the drivers listed on Canon USA’s page for the copier is just a bunch of Windows files. A websearch for ‘ canon iR5020 ppd turned up a Canon Aussie site that had a nice .sit file with a PPD in it. For future ease, I’ve placed this file here:
CNIR61U1.PPD
To use, just add a new printer, choose ‘IP Printing’ -> ‘LPD/LPR’ as the type, put in the hostname and print queue name, and then for printer model select ‘Other…’ and use the above PPD file.
Now I can print 2-up with duplex and get four pages on a single sheet of paper!