Take a double braided line and remove the core.
Yes, but Dyneema Blended Single Braids (robline racing, Swiftcord , Salsa) are very nice on the hands... unlike any double braid i have felt.
I use currently 7mm and think that is ok, if your main has not more than 15sqm. But agreed, it is pain in more than 20kts of wind. I guess 8mm is the good number.
That size was not available
