a rectangle bottom (11x15) with a square top ( turned on a angle. i have never tried or seen this. When I try to picture it in my mind it just doesn't look right! Let me know what you think?

how big is the square? Will it be small enough to fit on the rectangle and look like a diamond

I think the reason we don't see the rectangle and a square is the eye likes what we perceive as even proportions. But there certainly isn't any reason not to try it. What the eye perceives and what is reality can be altered by decorations, I would think. Have fun.

I'm new to this so take my suggestion with a grain of salt, but I would take my pans and turn them upside down, stack them and see how it looks. Hope this helps

Whenever I plan to do something 'different' I do just as Yellowdog suggested. Stack your pans to see if you like the look. I personally prefer using different shapes stacked together.

the square is 8 inch (I don't know where the smiley came from) I stacked them together and it still looked a little strange. Lapazlady has a good point though. I know I like everything to be even, but like my husband said it is not your cake.

I think I've seen it when there were several stacked to look like christmas presents. Looked good then. I think there are a few in the photo gallary.