There has been some talk recently about making a baby bonnet out of a hanky and some questions about a suitable edging. You can use any edging whether it's a really simple half ring edging, or a more elaborate edging made with several rows of tatting. Most commercial hankies are roughly 11 inches square and that means 44 inches of edging should be adequate. To make a hanky bonnet first tat the edging and attach it to the hanky like this:
Typically you wouldn't use a hanky with an embroidered flower in the corner, but that's what was handy, so I used it for this tutorial. Fold back about 2 inches on the front and stitch along the edge of the hanky where the lace is and it should look something like this:
Then fold back about 2 inches on the back, but stitch it about a half inch from the fold to make a casing. This will allow you to run a ribbon through the casing. When you tie the ribbon, it will gather the back of the bonnet shaping it.
Not having a baby head handy I stuffed it with a ball of thread to show you how the back looks.
To finish it off add ribbon ties on the front with optional ribbon rosettes or tatted motifs in the corners where marked with an X. Extra ruffles and nice on girls, but not as necessary for boys.
Depending on the size of the baby, you can make the bonnet larger or smaller by increasing or decreasing the size of the folds. If the baby is a preemie, you may want to start with a smaller hanky.