It's so easy it almost feels like cheating! :O
(My apologies for the low quality pictures. I can't find my camera.)
There's tons of t-shirt reconstructing projects but I've never seen a use for the neckline band. I didn't want to throw them out since they seemed like they could be useful.
Then I had a epiphany! Why not use the neckline band thingy for a head band! And it fits! I can never find headbands that will fit my head and so this is like a dream come true. ;D