If you go to Google and type in the words wedding cake contract quite a few things pop up
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And make sure that you take the randomly googled wedding cake contract to an attorney who can tell you if it will or won't fly in your state. You have to word things in a certain way in different places to make sure it would stand up in court if it did end up there.
It's less expensive than having someone sue you and have you end up paying their court costs. Chances are that wouldn't happen,but if you want to run a business you need to have everything in place before you start selling to the public. A well-written contract that outlines who's responsible for what payments when, who does what at the delivery, and who is responsible for what after the cake is set up and you leave will save a lot of headaches in the future.