Ok, it’s not much of a tutorial, since you could have figured this out on your own, but in case you are really new to this augmented apparel thing, here you go:
Dig into your spare denim stash (which you totally have, right? You cut the legs off knackered old jeans before you chuck them, right?) and choose a colour that will work on your recipient garment. Using your phone as a template, cut a rectangle as big as your phone plus about 2.5cm all round. Then cut a curved corner away, bit enough that your phone will fit into the pocket if that’s the opening. Bear in mind a bit of seam allowance.
Turn just a bit of the curved edge under and stitch it down. This will be easy if it’s stretch denim and a little harder if not, but it’ll work if you turn under only about 5mm. Stitch that down all along the curved edge. Don’t worry about the raw edge on the inside, it won’t fray much.
Plonk it on your jeans along the side seam, about mid-thigh. Turn under each edge about 1cm as you pin it in place. Adjust pins until you are happy with where it is and that it is not all wonky. Maybe stick your phone on it again to make sure it hadn’t got too small.
Manouvre the jeans into your machine and stitch round the perimeter, skipping the curved edge (obvs, that’s the opening) and reinforcing with some backstitching either side of the opening, where you’ll be pulling at it every time you take your phone out. Be careful not to stitch bits of the leg to the back of the work, but if it happens, it happens. Rip the stitches and do it again.
You are ready to go. Commence to quote various spaghetti westerns as you reach for your phone. And enjoy not having to stuff your phone in your stupid girlie pockets that can barely hold a tissue and are already on a fairly crowded bit of your anatomy if you’re shaped like me…