Once again...outstanding work. Question....is the bottom also a piece of flattened horn? And if so, how does it stay in there? Some type of glue? Beeswax? Pressure fit? Also, that beautiful polished finish on the edges, did you use some sort of buffing wheel? I look forward to more postings of your stuff as always. 
Thank you all for the compliments. LehighBrad...The bottom is a piece of flattened horn. There is a grove cut into the cup (a chime). the flattened horn is then turned round and to about .005 larger than the groove is deep. both the sides of the groove and the bottom are chamfered at an angle. approx 30 degrees on the cup and approx 60 degrees on the bottom. The cup is then heated (heat gun) until hot to the touch but not too hot to scorch. the bottom is placed on the cup and then pressure applied until it snaps into the groove. When the cup cools, if your measurements were right, it will constrict around the bottom and the cup will become watertight. If the bottom is too large, the cup will either crack or become malformed when it cools.
The finish on the edges...It is not polished...the horn was a very translucent piece to begin with. After turning and buffing with wax..I put it on the bench to take photos. the light source was above and flourescent and what you actually see is the light shining through the cup.
Regards, John
