Blue,
I'll echo the other guys on the RIT dye method. To keep mine submerged I use a few split shot fishing weights around the flashing on the edges. I like the idea of mixing the black and blue. I've used dark green and blue before, but I'm going to try the mix.
One thing about this method is that it does take TIME. I usually go at least 24 hours in the dye and another 24 to dry it. Make sure you don't rest it on any part of the canopy while it's drying or you'll get a spot for sure. Just be careful and take your time. The effort is well worth it.

papermache