Which Blank for a light Trout Spey Rod?

[RS1]

I don't think you want to build one (spey) under 12'. Big difference between a spey and a switch rod.
I have a friend that is into two handed casting and fishing. He does have some nice Echo Dec Hogan two handed rods in 4w, 5w and a 6w for light trout. The 4w is an 11'9" rod, the 5w is around 12' if I remember right and the 6w is 12'6". I used them last week. I'm not sure if you can get blanks for them yet. I'm not certain who makes two hander blanks in trout sizes either. These are NOT the same as switch rods they are "spey" type (two handers).
I just looked online and they go for $349 retail. That might be cheaper than buying grips, a nice seat, guides etc. If you enjoy fishing for trout with the two hander, maybe build you one later.
This friend used his 5w all last year on the Green and Provo rivers swinging softhackles and caddis. He has a hard time going back to single handed rods now. The lines he used were AirFlo Delta tapers in 4,5 and 6w spey lines.
Good luck in your endevor.