How can I make my arms FATTER. Not more muscly, just fatter?

Since I'm an ectomorph I get the delight of being able to eat virtually anything and having my body work it off overnight. But this comes with a heavy price: I have incredibly uneven fat distribution. I NEVER put on weight on upper body, waist or stomach; if ever it is always on my hips and my ocks. Now I don't want to have to do any weights or anything to make my arms larger because I don't want them to be muscly or hard just mildly squishy and...well the way normal arms are. Plus IT'S NOT FAIR that I have to do weights when other boys my age don't have to because their arms are normal size (I'm 14). Is there anyway I can build up fat on my arms without dragging my body down too much?