This project can be done for very cheap - or not. A lot of the tools can be replaced with other items, as well as the parts for the stool. Also, if you don't have an old motorcycle saddle, you could use pretty much anything for a seat. Anything that you may want to sit on, that is.
Step 1: Tools and Materials you will need (and some you may want)
1. Miter saw - makes cutting the angled legs easier
2. Table saw (optional)
3. Drill with drill bits and a paddle bit
4. Angle grinder/cutter (I used this primarily for cutting)
5. Rotary tool (this I used to grind a smoother edge)
6. Impact driver (optional)
7. Random orbital disc sander (optional)
9. Sheet metal step bit
10. Wood glue
11. Tape measure
Materials I used
1. 1 of 8 foot long 4x4 - probably didn't need this much, as there was some scrap left over - six feet would probably be enough depending on the height you want the stool.
2. 8 of 4" lag bolts or construction screws
3. 1 stool swivel
4. Scrap wood - you will need a bit, but it doesn't have to look nice or anything.
5. 18"x24" Sheet of heavy gauge steel or aluminum; I used diamond plate aluminum, because it was thick and I like the way it looks
6. 4 of 2" sheet metal screws
7. 4 of 1 1/2" x 1/4" bolt or machine screw
8. Motorcycle seat (or whatever you plan to sit on)
(Optional for wheeled stools)
9. 16 of 2 inch sheet metal screws
10. 4 ball casters