DIY Eno like UQ question

[tammons]

Pretty much decided I am going to build one of these out of M50 and 5 oz climasheild. Going to be 8'6" long and a total of 5' wide which will be wide enough to close the top into a pea pod of sorts.

My question is what should I use to fasten the top together ??

The original Eno had a sort of cord and toggle setup so you could fasten together but it would stretch.

I want to be able to really close it up so more thinking about a zipper but not should how it would hold up.

Opinions welcome.

[Mountnman]

If you are going to use a zipper just use some type of heavy duty that goes both ways to help vent it if needed