I rebuilt my top about 4 years ago, before CCOT developed their rain gutter. I bought a gutter from SOR or MAF, can't remember which right now. They cut the rain gutter into 4 pieces for me to ship and I welded it back up in the garage. I tried to find rivets to build it back like original but was unable to find them so I used stainless steel machine screws. I lined up the fiberglass top on the gutter, drilled holes and installed the SS screws with the nut in the top of the gutter. I trimmed off any protruding screw above the nut with a dremel (oh yeah, I used some red locktight on the threads). I bought some flowable sealant from a local automotive paint supply house and filled the gutter full (on the outside) to seal the gutter. Four years later it's still in good shape however, I don't drive it much and it stays garaged. I spent probably $600 on parts and paint. The sealer that I used was about $100 per unit and it took almost 2 units.
If I had it to do again, I would change a couple of things: 1) would pay closer attention to alignment of all parts including gutter, windshield, side panels, etc. all of these pieces have bolt holes that need to line up and mine didn't fit perfectly. 2) I would use rivets as the head doesn't stick up so far. I covered the SS screws and nuts with the sealant which totally filled the outside of the gutter effectively defeating the purpose of the gutter.
To do it right, your going to spend some money.
Good Luck,
James H.