yes, they are heavy, yes they are stable.. nope their not for sale
The tennis balls i use however, are..... In pet shops.
they sell some nice, very realistic spongy tennis balls for dogs.
Only a couple of quid each.
now because they are lighter, you may find that it solves the ballance issues with your existing cups.
you're like Yoda.you dont say much, but what you do say is worth listening to....
Greg Wilson about.... Me.