Maybe you could offer the winner a couple of options:
1) Very basic - this is a needle, this is thread, this is a sewing machine, this is fabric level - I think a pillowcase would be about it for three hours - and it still takes me longer than that to do it well.
2) Maybe a very small table runner or place mat thing - you could get -
3) Maybe a specialized class - how to apply binding - how to do flying geese - different ways of doing HSTs