Charge for the tools but let the levels be played without a fee? There's so much cool stuff available, but most people will never see it because it's hidden behind the initial cost of purchase.
Before signing up you best check how the payout works. So it's not like Roblox. Encouraged to create within the system but making any money is near impossible, and even when you reach the minimum payout limit, the conversation ratio is insanely bad.