I had two pairs of pants that were too short so I cut them and hemmed them.
These ones were also too big at the waist and kept falling down, so I put some elastic in the waist (like here) and now they stay up much better. not perfect but I don't need a belt any more.
I used a straight stitch instead of a zig-zag and stretched the elastic as I went.
Another shirt copied after my favorite one.
