I've been looking into Cinetatics' products. Great light way to mount a matte box without using a rig system. It's made of 'ballistic nylon'. OK, some traditionalists may not be too keen on the idea but I would appreciate a more lighter one if it can do the same job and reduce weight on my rig.Frankly I always wondered why matte boxes had to be made of 'hard' material. It's just something to block out light! And if you're wondering how to mount square filters, they have a covenient way too.
The Shoot35 CineBox matte-box has received some good reviews. ( A few of the members here at DvxUser have it. I bought their follow-focus unit and will eventually buy their matte-box )