The butterfly stamp is my very favourite - of course - and it's a perfect size for baby gifts. Of course, you could also adapt this idea to a larger garment, perhaps with a flock of butterflies! But for this project, I stamped the butterfly just once on a newborn sized onesie.
I stamped in pink then used three strands of embroidery floss to outline the full butterfly. I find it easiest to stitch on knit fabrics with a hoop, but it's best to stamp without the hoop so the design will be in the right place and not distorted. I just pop a piece of scrap cardboard inside the item so it's easy to stamp on the knit. Once you add the hoop, pull it taut but not tight - you don't really want to stretch the design.
The butterfly is a quite detailed stamp, so you could spend a long time following all the lines with your stitches! I opted to just add a bit of the detail in the top and bottom of the wings, then some wording across the middle. For the lettering, I just wrote in pencil and stitched over my letters. If that's too hard to judge, you could use letter stamps as a guide or print it out on paper and hold it up to the window and trace through the fabric.
The stamp ink will fade with several washes (unless you use special fabric inks) but I like this design both with the ink and with just the outline, so I don't mind if it fades. (Of course it's not for me so really I should just hope that baby and her mama don't mind!)
In progress . . .
Beautiful! Thanks for the inspiration Shimelle!