I designed this to be as close in shape to the classic prop from Star Trek as I could, but to be acoustic rather than electric.
EDIT: Here's an MP3 of me playing this lyre
EDIT 2: By popular demand I have added a schematic image with some dimensions. I didn't measure much of anything when I built it so i had to go measure the actual article to get these numbers.
Step 1: Basic Body
Then I printed the whole thing out. My printer isn't any bigger than yours, so I had to print it out in sections and then tape it all together. Next I cut out the whole shape, taped it to a big piece of 3/4 inch plywood and cut the sucker out. If you are a better free hand drawer than me you could probably skip most of that and just draw on the plywood. I was trying to get mine as close in shape to Spock's as possible so I was a bit anal.
Next I made a copy of it with some more plywood, then glued the halves together with some clamps.
Oh, uh, see that little area at the bottom that isn't cut out? Yeah, that's important, it does stuff. Namely it gives to something to screw the tail piece to.