By the time you spend the money on the parts alone not counting the time involved in building one you could buy a digital ballast from Elite. 5yrs ago when I built mine that was not the case. If your talking about "building" one, doing the copper winding and attatching the magnet then that would be nuts. Do a search for "magnetic ballast" or "ballast kit" and just take a look at those prices. Then check Elitehydro.com in their electronic ballasts tag, I bought the Lumatek but they have other less expensive brands as well. I spent many hours researching the same thing just a month ago before I bought the digi. You might be able to find a really cheap supplier for a mag kit that I could not though.