The Landsungkorps from S.M.S HABICHT had three artillery pieces with them when they fought at Lieuwenberg and Gross-Barmen in February, 1904. One was a C73 Krupps field gun from the Kamerun-Schutztruppe. One was a machine gun (and this was not the most effective as it was difficult to elevate sufficiently to attack Hereros on the heights above Groß-Barmen). The last was a revolverkanone, a 37mm Hotchkiss gun likely very much like the one shown manned by the sailor in an archival photograph below.
Tabletop wargamers in 25mm / 28mm scale are in luck if they are looking for a revolver cannon for the German Herero War of 1904, perhaps to play S-233 Assault at Liewenberg: The Main Line from the upcoming Sword and Flame based rules and scenario book by Roy Jones and Eric Alvarado.
Honourable Lead Boiler Suit Company. All it needs is a Brigade Games, Great War in Africa German sailor or two to man it, for unfortunately the HLBSC German SW Africa Colonial Line is no longer produced (and I'm not certain that it ever had German sailors even when it was). I have ordered this revolver cannon [as well as a smaller caliber variety], and look forward to its eventual addition to the lead pile arsenal.
Update (Nov 4th, 2013): Here is another option for a 3lb 37mm Hotchkiss gun, revolving cannon, but in resin, from Grandmanner.