With the Silicone Tank, you can control your breasts, lips, ass and hips. I think it would be logical and really convenient to control your cock size as well. Maybe 1 unit can have a consistent proportion size. Such as 1 unit = 1 inch + 0.3 inch girth or something like that. Or, have length and girth on two separate controls, that way characters with tentacle phallus can have more control over their independent proportions instead of keeping everything the same ratio.