Hmmm I'd guess a 6 - 9 - 12
i think mnsnow is correct...
Thanks guys, but I just tried this with the tins I have and with a 9" square it hangs over the edges of the 12" round underneath. See this is why I need to buy cake tins in every size then I could just play around!
i agree with the OP, look at the 6" there is hardly any room at the bottom of that. a 9" would have give 1.5" gap.
Sketch up program is discussed in this thread and would help in determining correct sizes for mixed shapes:
Great link Jan, thank you!
Small, medium, large LOLOL
my guess is an 8" round, 10" square, 14" round