For this crochet bag, I designed a retro-style graph pattern / pixel grid. The pattern for the bag is similar to the well-known checkerboard bags.
All you need are single crochets and a few decreases for the straps.

Materials:
300 grams of cotton yarn, I've used Rico Design Essentials Organic Cotton aran 50g 90m 4-5mm
4 mm hook (it should have a tight tension)
stitch markers, scissors, darning needle

Stitches:
sc - single crochet
sl st - slip stitch
fsc - foundation single crochet stitch
sc2tog - single crochet 2 stitches together

* Please tag me if you want to sell finished bags created using my pattern design!*