Sorry for the delay, I had time earlier today to lay in the seaming tape. What I use is called seaming tape. It comes in a roll and is sewn on the edges to it does not fray allover the place while handling.
http://www.fibreglast.com/product/Woven_Fiberglass_Tape_217/Fiberglass_Tapes
It's as simple as this:
1 - cut some tape to length
2 - mix up resin
3 - wet the seaming tape / glass
4 - remove excess resin from glass
5 - put in place
6 - blot with a paper towel so it does not look wet or puddled with resin.
7 - wait for a few hours to overnight depending on your resin and separate.
I did not plan to, but I did a quick time lapse of doing most of these. Every time I mention splitting cowls I get at least half dozen PM's asking how much I'd charge to do theirs. My answer is nothing because it is so simple you need to do it yourself!!!! As my wife
@thelaw would say.....suck it up buttercup.
The hardest thing is cutting the line.......which is not hard at all. Take your time and cut on the line. Does not get much more simple than that! Took my just over 15 minutes to do 5 cowls. Maybe 30 minutes to cut 4 of the 5 cowls (one was already split, just needed the tape).