I want to start a business in my barn, anyone know a niche to make big money? Worm farm, special plants, etc?

I have this commerical grade barn, concrete floor, air controlled, about 3,000 sq ft at my home property. It just sits empty and I’m desperate to think of a way to make some extra money. Looking for ideas to distribute, grow, or manufacture something that is possibly a hard to find or niche product I can sell to Wal-mart, or other big businesses. Any ideas? Thank you so much