Tenkara Fly Fishing line spool

I'm a designer and a tenkara fly fishing angler, I was wondering to design my own spool to store the lines...
I tried the one designed here http://www.thingiverse.com/thing:232208 by @ecleticangler and I decided to design my own spool with some features.
This spool is one piece with two place where to fix the fly and 6 groove where to lock the end of the line.
I placed a snap-on joint on one side that help to store two lines holder together! And the hole in the middle lead you to put it o