hey man i have heard of gus taking three old doors and hinging em together in a corner ...but you say you're handy? well then, from much advice i have got from friends who built there studio they told me somethings.
first fram up you're walls how ever big a booth you want(4 ft x 4 ft is plenty big for a single vocalist) then cover the outside with sheet rock, oh yeah dont forget to frame for a door if thats what you want on it, a heavy storm door can be got used and will keep sound out if thats nesisary. after you caver the out side tape the seams and cover it again then stuf the cavitys on the inside with insulation then cover the inside walls finish the walls what ever way you're gona then on the inside cover the walls with sound foam it will sound great my friends is sweeeet! oh dont forget to make some way for you're cables to get in and out...
need more advice just ask.