Tried the sports ball for the first time to make a big golf ball. Cake/filling/settling all went fine, but I'm not getting a truly round shape as I smooth the icing. I've used paper towel with my hand, with a fondant smoother--even an upside down bowl. It still isn't spherical--especially evident when I spin the turntable. Any suggestions?

I can't tell from your post if the problem stems from the frosting application or the shape of the CAKE itself. I'm going to assume the former since you mentioned smoothing with paper towel didn't help.

The only thing I can think of is something I saw on a show once. You take a flexible piece of plastic (I think, or it may have been a piece of parchment paper cut into a triangle shape - it's been a while since I saw it) and used it to smooth the frosting. That way, it could arch as she drug it across the ball when she frosted it.