I need to make an 8 inch ball. The biggest ball pan i can find is a 6 inch.
Whats the best thing to use for making the shape as i really dont want to try and carve it out of 2x 8 inch cakes.
Any help would be great.
Thanks

Do you think you can find a stainless steel or pyrex bowl with dimensions you need?
In a pinch I use even cheap glass bowls made from thick glass, not even oven safe. If you need it only once, it should work. Look at your local second hand store or similar.

If you need to carve - I wouldn't actually start with 2 8inch rounds. Again, I would search my bowls and casserole dishes, if anything comes close. Else, I would bake a sheet cake and cut circles with different diameters. Stack it (roughly 2 half balls), carve, stack again.
Or bake one 8 inch round and one 7 inch round for carving, or for minimum carving two 8x4, one 7x2 and one 5x2 inch - split the two smaller ones for 7x1 and 5x1 on top of the 8x4 for the half ball.

It is easier to carve if you have the rough shape - not carve ball from a cylinder.

Actually I just made a ball shape this weekend and it was really easy. I used 3 - 8 inch cakes. All together, they were 5 inches tall. I carved the top to a round shape first using a 6 inch cakeboard as the guide for the top and then did the same thing for the bottom. I had a board on the bottom and just carved it in to the board then rounded it all off. Easy! use a variation of the WASC cake and froze it first.