"How cool is it that I can call my family in Florida and they can go see my box?" Sinclair said.
The boxes will be in restaurants this summer and fall, The Krystal Co. said.
Rauch said she urged her friend, Sinclair, to try the competition after she found the contest on Facebook. The two friends often take their families to the Krystal on Martintown Road after attending church together on Sundays, Rauch said.
Rauch said she submitted more than 10 designs. Sinclair, who said her cake-decorating skills helped her, entered about 30 creations.
"To me, it was just like a blank cake," Sinclair said. "I found it very fun."
Two of Sinclair's designs won judge's choice awards. One features an owl with the words "Whoooo doesn't love Krystal."
Sinclair had Valentine's Day in mind with her other drawing that features hearts to represent her love of Krystal, she said.
"I absolutely love their fries. Their fries are the best," she said.
Rauch said she always had an interest in advertising.
Her winning box reads, "Stop and smell the Krystal's along the way." Three flowers surround Krystal burgers in the design.
The third North Augusta winner, Collman, said his winning design was his least favorite of the five he entered.
Collman's box shows an outline of the Krystal store on Walton Way in Augusta, he said.
The company received "thousands of submissions and enjoyed seeing how our customers represented what Krystal meant to them through their designs," Krystal said.
Judging criteria included creativity, graphic design and votes from community members, the company said.