Here are the quick and dirty steps I followed:
1. Select your bra-top camis to dissect. If you don't have any, your local thrift shop might be a good place to look - I almost went to see if I could find mine and buy them back. I suggest bra-top camis because I found that the elastic band at the bottom of the "bra" was useful.
2. If you have an existing belly band that you like the fit of, measure its height. For mine this was 10".
3. Prepare to cut your camis...First, turn the cami inside out and measure the height you just took onto the cami plus 1" to give yourself a little room for attaching elastic. Mark with pins or however you normally mark your sewing cuts, then snip away. After cutting off the tube, also cut the elastic band from the bra top portion of the cami. You'll end up with something that looks like this:
You'll notice that in this case, the elastic band's circumference is less than the tube's circumference. In order to correct this, I cut the elastic band on its seam and also the tube on a seam and attached the band to the tube, than cut off the excess part of the tube.
Then I sewed the elastic to the unfinished side of the tube portion (the side that you cut) and reattached and sewed the vertical portions together to recreate the tube.
If your tube and elastic are about the same circumference, you'll be able to skip this step and go straight to attaching the elastic band to the unfinished side of the tube, which I was able to do for the second band.
Here are my two finished bands :)
You'll notice that the light blue one is a little rough around the edges - sometimes I have a hard time remembering which side is the right side to sew on. As long as you put a little thought into it, you won't have the same problem I had.
And if you're wondering why I attached the elastic instead of just finishing the top (cut) edge - it was really just a trial and error decision. Luckily, I don't think it was an error - when I was still small enough to be able to partially zip my pants, the elastic acted as an anchor when it was used a little above my waist - the finished edge just covered/smoothed out my unbuttoned button under my clothes. Now that I can't zip at all, I'm using it at the bottom to secure my pants from falling down and the rest still takes care of the smoothing functiuon.
Are they perfect? No, I still like my store-bought one better, but for the price, they can't be beat. My only real complaint is that I have to monitor where my pants are a little closer after standing up from sitting, which I have to do with the other ones anyways, just not as much.
