I'm short, so it's more of a dress on me but if you want to make your own (very unprofessionally) as I did, then here's how:
1. Using a pair of fabric scissors, cut the sleeves off your shirt of choice. Make sure to cut the fabric right up against where the edges have been overlocked, to minimise fraying.
2. Put the shirt on either yourself or your a model.
3. Fold in the fabric on the shoulders until you are happy with the look of your shirt, and secure with pins.
4. Sew the shirt where the pins have been placed, and make sure no pins are left in the shirt after.
Alternatively, (if you don't trust yourself with a sewing kit) you can visit www.topshop.com and view their range of sleeveless shirts, priced between £18 and £33.