Rava kept track of how many cups he drank by counting beams. It seems a strange way to keep track. I use fingers to keep track of the "lamnatzeach's" by shofar.
looking up at the lights or ceiling tiles and using them to keep track doesn't seem very helpful to me.
Empty cups or perhaps tying knots in a gartl might be a way, if one needs fingers free to eat.
Thank you
Alex lebovits
The Rambam states that just as people's faces differ from one another, so too, do their ideas (One man's meat ... ).
For a variety of reasons, Rava might not preferred not to use any of your methods. For example, he may have avoided using fingers for the reason that you yourself suggested, or because fingers can be opened and closed, beams cannot!
He may not have worn a gartel which is 'knotable', and for all we know, he used only one cup which he kept on filling.
Come to think of it, counting beams seems an excellent idea, particularly if the beams were large and significant (which they probably were).
Be'Virchas Kol Tuv
Eliezer Chrysler.