Hamster balls are not really safe for sugar gliders. The air slits can catch the long glider 'fingers' in the slots and cause broken or even amputated toes.
Gliders also pee and poo while running around which means it would be slinging around in the ball and all over the glider.
There is a safer option for allowing your gliders to run around in a confined space called a Run-a-bout
http://www.spinzoneglobal.com/Runabout_c_13.html
Hamster tunnels are too small for many sugar gliders - and too small for you to reach in and get the glider if necessary.
I have Ferret Tunnels in my cages that my gliders love to climb around in. The larger tunnel allows me to reach my gliders in the tunnel if necessary or just to reach in to hand them a treat.