For example, I would like to change a cube into a sphere, then change that sphere into a capsule, by pressing the up arrow. I would also like to be able to change in the other direction. Change the capsule into a sphere, then change the sphere into a cube, by pressing the down arrow. It would be great if i could add extra objects in, say a pyramid etc.
Ultimately i would want to do this with something like a seed, sapling, and tree. Each with there own properties.