Just got my aqua-mag jr. Can't really give much of a write-up.
Basically, it's made out of very light material, plaster-like. The magnet sits flush to the glass, so no gap or anything. The material is very fragile and easy to break in your hand.
The one thing I'm weary about is that the one magnet holding the rock is in the center allowing for the rock to spin on a fulcrum. Center of gravity is pretty neutral.
It's a bit bigger than I expected. I haven't figured out placement yet. And I'm hoping it turns purple fast! Looks crazy white now.
Pics to come - I'm over my quota.