Here’s a product that has a unique twist on defying the gravity of heavy objects, in other words lifting weights.  Neopreme disk-shaped containers for holding sand or even steel bearings.  Higher fluidity of the medium being lifted engages more muscles for a harder workout.

“Hyper Wear’s SandBell is a cross between a sandbag, a dumbbell, a barbell, a grip bag, a medicine ball, a slam ball, a stability pod, a gliding disk”

http://www.hyperwear.com/