Thanks @vliet, but as you know after a while in crochet you apply a common set of principles.

If you want a flat round shape you need to increase at 'regular intervals' and if you change that or include decreases, you change the shape...

In a way I use similar principles to the stress balls that @ivan-g crocheted some time ago for the squirrel head, by adding the 'nose bit' I ended up with an oval shape.

I'm now working out the body shape, so if I start from the base, that will be a flat round shape. In a way it will be similar to @mrscwin's crochet colour pop baskets.

I may just use a more oval shape though... I'm considering the options at the moment.