My results from this event:
No diamonds spent.
27 total tablets, 1 full set, 7/8 for a 2nd set (missing gold tablet).
37 gems found - plenty to complete the calendar
around 10 daily specials spread over 5-6 different types, will go back and double check eventually (have everything recorded)
13.5 grand prizes completed
14 ferris wheel levels. 2 level one buildings, 3 selection kits (1 from event surprise box, 2 from calendar), and 9 upgrade kits.
That means that, unlike the spring event, it is possible to get a full event building for free without diamonds, even if you don't have the event surprise box or go for the calendar. Even if I didn't get a full tablet set, I would have had enough without the event surprise box or calendar (11 total levels).
No diamonds spent.
27 total tablets, 1 full set, 7/8 for a 2nd set (missing gold tablet).
37 gems found - plenty to complete the calendar
around 10 daily specials spread over 5-6 different types, will go back and double check eventually (have everything recorded)
13.5 grand prizes completed
14 ferris wheel levels. 2 level one buildings, 3 selection kits (1 from event surprise box, 2 from calendar), and 9 upgrade kits.
That means that, unlike the spring event, it is possible to get a full event building for free without diamonds, even if you don't have the event surprise box or go for the calendar. Even if I didn't get a full tablet set, I would have had enough without the event surprise box or calendar (11 total levels).