answer:I don’t think building it would be the biggest challenge. Friction is the basic principle behind most fire starting techniques. Friction ,even a small amount, would still ignite something flammable. Keeping it burning, or should I say finding a decent fuel would be hard. Most small things would burn quickly and then the fire would go out. Maybe you could find a slow burning mushroom, and ignite that… You couldn’t get it going too big, or you might be too slow to run away. Being so small,but with our anatomy and physiology ,you wouldn’t be able to cover ground quickly.