|1-19-06 Edited to add photo link above.
I first decided to do this because I had some cute T-shirts,
but I never wore them because I couldn't stand the high neckline. I found that I liked the result so much, and that the possibilities for creativeness were so great, I started buying packages of men's white T-shirts [3 in a pack] as 'blank canvases'. I like to get a size small enough that they really fit well in the shoulder area. Smaller size women might want to buy boy's size.
I make a pattern for altering the neckline by laying the shirt out flat, tracing the shoulder lines onto paper, then mark the edge of the neck and sleeve seams. Cut this out with 10-12" of paper left below. Put the T-shirt on, put pattern up to match shoulders, and mark the center front to show how low the neck should be on you. Remove pattern and fold in half at the center front, matching shoulder lines. Now you can draw a different shaped neckline on half of the front pattern, going no lower than your mark. I like a scoop neckline. Cut out both halves at once while it's folded, so the new neckline is even. Hold the pattern up to your body and see if it looks right, adjust till it is. You now have a 'negative pattern'. Lay T-shirt flat, pin pattern on, matching shoulder lines, and mark around the negative space or new neckline.
Before you cut anything, you'll need to stay-stitch the fabric 1/4" outside the new neckline. This seems awkward, to get the back half of the shirt under and behind your presser foot, but just take your time. Start at the center back, normal stitch length, and stitch 1/4" away from the original neck band, following around to your drawn line, sewing 1/4" outside the line. Avoid stretching the fabric before it reaches the needle, and pull on the fabric/stitching behind the needle, so the fabric/stitching doesn't pucker. Remove from machine when the new neckline area is stay-stitched. Now you can get rid of the original neck band, cutting 1/4" inside of your stitches.
Apply double fold 1/4" bias binding. I like to open up the binding, and sew the right side of the binding to the wrong side of the new neckline, then fold over and top stitch. Steam press to set your stitches and form the bias. The binding can be purchased bias tape, or you can make your own.
This type top is wonderful to wear under a jumper, and the
binding can be made from the same fabric as the jumper, to have a quick easy matching top. Since it's close-fitting, it doesn't bunch up in the arm and upper chest area, like most blouses do under a jumper.
Another great use for these is to wear under cute summer tops that have spaghetti straps, so you can extend their wear into fall and spring.
I referred to these as a 'blank canvas' because there are so
many fun things you can do with them. Dyeing, fabric paint,
appliqué, beading the neckline...just to name a few.
Bias can be applied to the sleeve edge too, but you'll lose some of that comfy stretch of the T-shirt. Once you've changed the neckline, they really lose that 'regular ole T-shirt look'.
A package of 3 white Hanes men's T-shirts costs like $5, so you can 'play' and not worry about wasting much. I have to say, you don't want Fruit of the Loom brand, they stretch out of shape almost immediately after you put them on.
Oh, and be sure to prewash and tumble dry them before sewing, they shrink.
9-19 Edit...be sure the new neckline is big enough to go over your head, because the new bias neckline won't stretch.