3/4 inch electrical metalic tubing bend measures .922 out side, 7/8 equals .875 pretty close, maybe a wrap of electric tape will make the difference up and prevent scratches. they will bend about a 5 inch radias. go talk to your /friendly electrician
Make friends with someone who works in an auto exhaust shop.....they bend exhaust pipes.
Bimini...I do have a thought. I had one built some years ago and got about 10 years out of it before it became something that I just didn't want to repair anymore.
I would not put zippers on a bimini. Zippers are there to make it easy to take off and the only reason we ever took ours off the frame is because the zippers failed. My next bimini will be manufactured with reinforced sleeves for the frame, but no zippers.
I had a window (plastic) put in it so that I could check the sails - that was a good idea, and I'd do it again.