I have a shade structure with a hot tub underneath, I want to make a greenhouse out of it. Besides 6 mil uv protected plastic what other ways can I cover it inexpensively and still let light in.?
If you just want shade check out the shade cloth at Harbor Freight. We use that over our 6mil in the summer. You can also do lattice, grow vines, or use palm branches.
But if you really want a greenhouse, you want more than shade; you want an enclosed area. You could use those sheets of wavy plastic that are used for patio covers & things. (bad description, I know) But it can serve for both walls and roof. I'm sure it would be more expensive than the 6mil, though.
We ordered our 6mil online; can't remember the vender offhand but I could find out. We got 16'x100' for around $115. Not bad considering it'll cover our greenhouse twice. Other than that, keep an eye on Craigslist for any kind of materials & use your imagination! :)