A little variation of the lottery:
Guess the amount of vouchers I have:
0 guesses: 1x cake, 1x ice cream, 1x coffee product or 1x juice at your choice for all partecipants (individual product subject to availability).
1 guess: in addition to the above, 1x jewelry of choice or 1x silo material of choice
2 guesses: in addition of prize for 0 guesses, 3x jewelry of choice or 3x silo materials of choice or 3x barn material of choice
3 guesses: in addition to prize for 0 guesses, 5x bar of choice or 5x barn material of choice
4 guesses: jackpot! 20x planks!
NB in this case "zero" could also be an answer. 10 min starting now!!!