Wait how would they make rainbows before modern technology?I know it sounds weird but think about it.If there wasn't any machinery how would they do it.My theory is that they had to do it by hoof.I mean there is no other way (I think).And that must be horrible for the poor foals.They would needed a better , quicker , more efficient way of turning the kids into rainbow and that's when they would have invented the machine they use today as that gets the job done quick and efficiently