You can find the Sandbox here.
Have a question that you want to fix up or not sure if it'll be a good fit here? Or looking to help nurture the community and help increase the quality of questions on the site? The Sandbox is now open for business!
The Sandbox will be a community effort. I'm going to be lurking around in it trying to comment and help questions that get posted, but we can use your help too! If you're a newer user or want to make sure your question is the best it can be, I'd encourage you to post in the Sandbox first. Likewise if you're an experienced user and have some time to help out, you can always drop in and leave a comment or two on how we can shape up our future questions.
Have a question or comment on how the Sandbox is implemented? I've added the sandbox tag, so if you have questions on how to use the Sandbox or comments for things we can do better, please post a Meta question. Criticism is welcomed!