Made this dress the other day from a tank top and an XL men's t-shirt.
I've been getting frustrated with my lack of clothes that fit vs. the short amount of time I have left before the baby is done incubating. Which is to say, hardly anything fits anymore but I only have a few weeks left, so I don't want to bother with making (or buying) fancy new stuff.
I cut the tank top off under the bust, saving the lower half for the belt. I cut the t-shirt into a trapezoid and sewed the new side seams. Then I just sewed the two together at the 'waist,' easing them together. I cut the bottom of the tank into strips for the belt, sewed them and turned them, then hand-stitched the belt to the back of the dress for about 10 inches.
This was another experiment in sewing with knits. I can now say that a single (interlock, jersey, whatever) knit is relatively easy to sew, but a ribbed knit is more of a pain than silk chiffon. It's just soooooo stretchy. Without a serger, there is absolutely NO stitch that has enough stretch. I got the dress together fine, but the belt was hell. I'm sure my seam is going to pop at some point. It's fine while wearing, but tying and untying it are more delicate.
It's comfy and economical, though. And it shows off my bump so well. ;)