Not so sure this is working for me, but I'll throw it out here in the "for what it's worth" category.
I modified the file from the globe sliceform and created an orange.
I think I like it better with the top cut off, so it looks more like a grapefruit.
It still looks weird. Does it need more horizontal pieces? Should everything but the top of the largest horizontal piece be solid orange?
Greater minds than mine have been mulling this over. Check out David Cecil's version in his surform set. (Now I know what this form is called!)
Extreme Cards and Papercrafting: pop up cards, movable and mechanical cards, digital crafts and unusual papercrafts.