1. Buy a cheap white shirt, mine was 1 pound from a local thrift store. I was lucky because it had a few cute details like a delicate button strip, small pocket and cute collar. I used leather from a pair of old leather trousers.
2. Lay the collar of the shirt onto the underside of the leather (the rough side) and traced out the collar onto the leather in chalk. To make the collar as polished looking at possible, I traced the collar with the outer edge along the hem from the trousers, so that it wasn't rough.
3. Cut the leather collar out of the leather, cutting along outside the lines of the chalk so that you don't accidentally cut too much.
4. Lay the leather collar on top of the collar of the shirt to check the size, snipping any extra leather off and generally shaping the collar.
5. Using plastic fabric glue (from the pound shop - nothing fancy), glue the collar down. I put the glue directly onto the shirt collar and attached the leather piece over the top.
6. Let it dry.
Viola! Wear with cute shorts. Mine here are also DIY...