I’m sure you’ve had a situation where your favourite garment finally broke… And you may never find such a perfect pair of jeans again… Don’t throw it away, COPY it! It’s pretty easy even if you don’t have a lot of sewing experience.
Start by cutting the garment up along the seams. Try to analyse how it was put together as you go. Once you have your pieces they will be uneven and maybe broken, but put them down on pattern paper and start drawing around them. If you see that the fabric has been shaped to your body over time (see the example below on the knee part of my pants), try to draw a straight line there instead.
Once you have drawn out the pieces on paper, straightened up the lines, you need to add seam allowance and grainline to your pattern pieces. Once that is done, you lay out your pieces on double fabric, pin it to the grainline and cut it out.