New spin on my “only accessible via warps” idea
We rename the creative worlds the “Dream Realm”
To get there, you take a nap and your character appears where you last left off in your dream realm adventure (or a sanctum in the clouds if it’s your first time). Perhaps dream sanctum can highlight 10 builds per month or something like that. You can take a nap via the menu or by interacting with a placeable bed object.
You can warp anywhere you want in the dream realms for free. You can also fly and swim in lava, you don’t experience hunger, and pies are free.
Obviously any items you may have in your inventory don’t return with you when you awaken. (Though I like the idea of tokens you can get for completing mazes and puzzles that can return to the waking realm)
Dream portals can only go between dream worlds and are made with dream portal conduits. They don’t require fuel. Maybe make the portals white colored, like clouds
When you awaken your character is back where you started. Kind of like Zelda: Link’s Awakening IIRC?