Okay, boys and girls, pay attention. I'm going to tell you the best way there is to make a CD sleeve out of a single standard 8.5 by 11 inch sheet of paper. I've made a lot of these, so I know what I'm talking about. No measurements needed... this is quick and easy.
You're going to want to use a bare CD as a guide. Lay it flat on the paper, and cover it over, just like you're tucking it into bed. The CD should be completely covered. There should be an overhang at the top there, about a finger's width.
Now fold in the sides. That one narrow side should be at least a half-finger's-width, and everything else goes into the thick side. Not too tight, now, we want to be able to slide the CD in and out without any problems.
Slice off the thick bit, leaving a ledge so that the whole thing is symmetrical. Cut out little triangles so that the top flap is a long trapezoid. Basically, right now, you want a rectangle eating itself on the bottom, and a wee little roof on top.
Now comes the hard part: roll out a strip of Scotch tape, and hold it lightly between your two fingers. You want to affix this tape to the skinny side flaps so that half of the tape hangs over. You then need to press it down firmly and slowly so that the edge flaps are fastened to the underbelly. Also, make sure to have a little bit of tape peeking over both the top and the bottom, but don't let it stick to the roof or to your workspace.
You're going to want to fold those little tape overhangs.... the ones on the bottom curl around to the face of the sleeve, and the ones on the top curl into the interior of the sleeve itself.
And just like that, you're done! Sign it, crease the top flap, and ship it out!
Okay, I know this was boring and lame. But no one should have to reinvent the wheel, here.