You can use any shape. It doesn't have to be a bunny. Just trace a shape or cookie cutter. This would be cute for any holiday, just use an appropriate cookie cutter to trace and cut out the shape, then whatever yarn works best for that holiday!
Had when i worked in a preschool and kids love them! I would use colored sand instead of white salt. DIY salt tray with alphabet cards. Easy to make and kids have fun smoothing out the salt after correctly making the letter