How about TH and DH (or BH for 'both-hammers'), with BB just assumed? I have been using NH for 'no-hammer' for quite a while, and I think others have too.
Agreed that BB can safely be omitted. No one is going to assume a pie factory stage. On the rivets board, the terms "weave" and "star" imply the number of utilized hammers.
Against my better judgment, the geek in me wishes to make an appearance.
For the items immediately preceding "hammer", I prefer consistency:
1H and 2H (self-explanatory)
SH and DH (single, double)
TH and BH (top, bottom)
Let's round out the group with a few more examples. There are plenty of others. Don't take them seriously.
UH and LH (upper, lower)
AH and BH (above, below)
SH and BH (summit, base)
ZH and NH (zenith, nadir)
I would most likely use 1H and 2H. Both are intuitive and unambiguous, although technically not acronyms. Then again, I should point out that none of the terms we've defined are really acronyms; they are initialisms. The difference is whether the item is pronounced as a word, or letter by letter (ex: NASA is an acronym, FBI is an initialism).
SH and DH are less obvious. Whenever I see DH, I immediately substitute "Designated Hitter", even though it has nothing to do with DK.
TH and BH are ambiguous. BH can represent "bottom hammer" or "both hammers", although use of the top hammer can be inferred from either one; "both" is explicit, while "bottom" is suggestive. Unless the timer is an issue, how many players skip the top hammer after taking the bottom one?
Final Recommendation: It might be best to
not include any of these in the master list. They're probably unnecessary.
Before anyone comments, I already realize I'm thinking way too much about this.