I had a bit of a bag clean out recently, quite a few were very tatty and for someone who rarely wears makeup a lot of my bags seemed to have lip gloss squished into the bottom.
I bought a couple of pairs of leather straps off Etsy recently (search for leather handles, you will find lots) and used a pair about 16" long with some fabric called Stamped by Ellen Luckett Baker.
I drafted a pattern and made the lining first so I wouldn't waste the good fabric if it all went wrong. I added a pocket for keys and my phone and some sew in magnetic snaps to close it.
I added a couple of pleats to the bottom piece and some darts to the bottom to add shape.