637 form

This is for all the tyers who are in the business of selling jigs.
Have you ever heard of a 637 form for the IRS? I've been laying my excise taxes and filing a 720 form for a couple of years now.
A local tyer stopped by my store yesterday and we were talking and he mentioned having to get a 637 form. Seems like you are supposed to have your manufacturing business registered. They even sent an agent out to inspect his basement before registering him.
The agent asked him how he found yto register. He had been asked for the form by a supplier and told the IRS agent. Agent said he has only done 3 in his several years of work.
So, anyone else heard of a 637 form. I downloaded it yesterday and it does seem like it's needed?

I filed and got my 637 status and what a mess. I ended up having to pay 15% for everything I manufactured. A real headache keeping the books for the IRS. I would not do it again. This is designed for big business and they are not looking for small time tiers and jig makers in my opinion. I thought I was going to sell big and even got 2 patents and boy was I disappointed. Weird business!!