Yes. You'll be able to create a floor in the floor builder, and then play it after you've saved it in the floor player. It's going to be a main addition in the May Test Build, so I've been spending a lot of time working on it.
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Well, if you're sharing a download link to a zip file of your custom floor (with the floor's folder contained inside of that) to one of those places, then yes, you can do that. So much creativity is going to be possible with the floor customizer, here's an example of just one type of floor you could make, a cloned characters challenge!