Pretty good response so far: My count is 49 entries in just a few days, which is more than I expected for the whole thing.
If it reaches 60 I'll add another prize. Then again if it reaches 80. That will keep the chances of winning reasonably good, but 4 will be the limit. I already know what the extras will be - a non-bottle, bottle collecting related item, and then another American pontil. The only way anyone will find out more detail is when the number of entries goes up!