Basics?
If I were constructing a metal flute headjoint (And believe me, I'd be interested) I think that I'd need a few things. This is my take on what is needed from a person who has never tried.
1) A quality metal lathe.
You need this to create the taper on the tube of the head joint. You use the lather to form this "paraboloidal" taper on a steel rod and then the tube is drawn and formed over this taper so that the tube takes on the exact bore shape. If you are "copying" an existing head you may be able to make a casting with plaster of the inside of that head and then take extensive accurate measurements of that casting to create this taper tool on a lathe. This would involve some other tools such as:
2)Micrometers for measuring things such as the tube diameter and taper as well as specific shape of the headjoint hole area.
3)The ability to make "lost-wax" castings of (possibly) the taper and the riser for the embouchure hole as well as nicely formed crown.
4)Jigs for locating the riser and the embouchure plate.
5)Tools for cutting and shaping such as a drill press or a small Dremel tool.
6)Equipment for plating the finished product for a more finished look.
This is where a class like Kara mentioned comes in to be a practical alternative. In a classroom situation, you have instruction which cuts down on the variability of your mistakes. The mistakes cost factor rises with the type of metal you know. For example: Is your head joint going to be solid silver or platinum?
Which brings up the other alternative...wood. You can make a head joint out of wood which may satisfy your interest in this project. You still need to make a tool to bore out the inside of a block of wood and then something to cut the embouchure hole. If you want, some metal tubing for the socket/tenon for your flute and a way to fix the metal tube to the wood.
Something for finishing the wood such as sandpaper and bore oil. Wood heads can sound very traditional and beautiful.
Now the easiest way to go is either Bamboo or PVC pipe. With a saw and a drill, you can create some interesting experiments for almost pennies. This would be the complete simple flutes w/o any keys to mess with...and it's educational as well as fun to do if you don't poke yourself with the drill.;-)
http://www.markshep.com/flute/Pipe.html
http://www.cwo.com/~ph_kosel/designs.html
