the easiest DIY in the worrrrrld
Take 1 T shirt & a pair of scissors. (I used a male L t shirt) Lay it flat
Fold the sleeve over on its self, then once more to same width as the sleeve (Does that make sense?!) this helps you know where to cut
Cut in a curved line from where the sleeve met the side hem of the t shirt
when you reach the sleeve cut diagonally outwards to get a cap sleeve
old vs new sleeve
Do the same on the other side!
Cut the neckline as low as you fancy, I cut downwards from where the collar met the hem along the shoulders, but in the past have just cut from should to shoulder (kind of boat neck style)
Obviously you can make the dropped arm hem as low as you like, but bear in mind what you might wear underneath!