Well, at least 1 has been made :-)
Since I don't own a 3D printer, this unit is printed by the excellent CM3D service on 3DHub (See https://www.3dhubs.com/los-angeles/hubs/cm3d).
Only external support is needed. Although the chamber is hollow, it is a smooth gourd shape so no internal support is needed if you print the model vertically, i.e. neck pointing up.