Interesting question.
Since SVSound switched from the industrial fabric to the velour, the current DSP cylinders look a little nicer than the old ones, but they're still a very basic, black tube, aren't they?
I haven't really come across ready-to-order custom covers. I'm sure Nathan Funk over at Funky Waves could probably whip up anything you like though
SVS might have some ideas if you contact them directly too. It does seem like a simple enough idea, but you're right, I don't really know of anyone offering such a product/service since it would be such a custom and niche market.