I think your design is great, I love the whole black and white designs; so elegant. Why didn't you get MDPC-X sleeving? It's only about $1 a meter with shipping and the dollar conversion. To sleeve a 12" 24-pin extenders, or just 24 wires at 12" each is about 6 meters
I myself used techflex, but no matter what angle I look at it, how
much light, and however good my macros are I CAN NOT see any wires through it.
Good luck on this, it's goingto be fine.