I think there have been other posts on this subject and i am probably not the inventor of this Idea but i wanted to share with you, my method of making Headers and Velocity Stacks from scratch.
I use aluminum and brass tubing along with solder wire (non flux prefered unless you want a mess later, it leaks out)
I have an assortment of different length and diameter of screws along with some other gadgets that i've found along the way.
The cone things on the left are tips from pens and drafting pencils.
The basics behind this is to use the flared end of any of these things and press it into the tubing.
This is a Grabber screw that i cut the threads off of with my Dremel and a cutting disc so all thats left is the smooth shank.
Select a piece of tubing slightly longer than what you need and find a screw that fits as tightly as possible inside but it has to be shorter than the tube.
Then i put it into a small vise and twist it till the head of the screw flares out the tubing.
Here's what i end up with. There is a trick though, make sure that everything is perfectly straight in the vise when you twist it or can bend the tubing sideways.
I know i have seen people set a punch on the tubing and tap it with a hammer, but this method gives you more control over how big the flare needs to be. I have even put a hole sizer arond the tube so i can press multiple piece to the exact same size.
I'll post another method in a minute..