A few weeks ago I made this bag. I used a pattern called "The Margaret Sling bag" from Oh ,Fransson!. It was pretty easy to make and it came with very clear instructions. I did make a few adjustments; like the size and the use of 2 different fabrics. I also added a zippered pocket on the inside and instead of a button I used a magnetic snap.
I don't know where I got the striped and blue fabric,
I do know the grey fabric is curtain fabric from here.