This is so unbelievably easy that I can't really count this as crafting. Although I never go out with my hair up, I do tie my hair up at home sometimes. I have seen ribbon hair ties on Etsy for awhile now, and as cute as they are, I've never been willing to pay almost $9 (including shipping) for these things. Two weeks ago, I saw that someone had pinned a tutorial on how to make these hair ties so I followed it and made my own.
All you need is some foldover elastic (the tutorial recommends elastic that is 5/8 of an inch), a pair of scissors, a ruler, and a lighter.
I bought a meter of foldover elastic from Stof 2000 for 9 kr (about $1.60) and made 5 hair ties. Simply measure and cut a 9 inch strip of elastic. Fold the elastic strip in half and tie the ends in a knot. (You can choose to use the shiny side of the elastic or turn it around and use the matte side. Or do both!) Pull the knot to make sure it is as tight as possible. Take your lighter and quickly run the flame over the ends of the hair tie so that it does not fray.
And there you have it, your own ribbon hair ties!