This is Samuel and I will discuss this and provide you information in this regard
So are the "hand spinners" is a non profit organization?
The Missouri Attorney General has reported that A raffle is a game in which a participant buys a ticket for a chance at a prize, with the winner determined by a random drawing to take place at a location and date printed on the ticket.
Missouri does not allow any organization to organize or participate in raffles unless they are recognized under federal law as a non-profit charitable or religious organization. So being a non profit is going to be key.
In addition, it can be argued that an Essay is not a game of chance but instead a skill.
The Missouri law defines a game of chance in this regard
(14) "Games of chance", any gambling game in which the player's expected return is not favorably increased by his or her reason, foresight, dexterity, sagacity, design, information or strategy;
To be clear on this, however, I suggest you check with your county commissioners and they can help you to get a permit, if needed.