Supplies: you will need fabric, clip buttons, and a strap. For my fabric, I used leftover charcoal wool as well as a red polka dot cotton for the lining. I recommend using a thick fabric here if you can, so that your clutch bag gets a bit of structure and doesn't end up being too floppy. For the strap, I used a chain from an old bag I no longer use. A belt would be really cool to use here (and I reckon a brown leather belt would have worked really well will my charcoal wool here actually).
First, cut out two squares from your fabric, measuring 45 x 45 cm. Pin right sides together, and sew around, leaving a gap of around 5 cm. Cut off the corners, turn it inside out and hand stitch the gap. You should end up with what basically looks like an empty pillow cover. Now for the folding bit. I struggled to take pictures of this, as the contrast between my fabrics made everything go all white if I focused on the wool, or made the wool go super dark if I focused on the inner lining (clearly I need to go out and practice with my SLR more). So instead, I made a diagram in Illustrator to show how to fold the bag (clearly I also need to practice my Illustrator skills more—I swore like a sailor while drawing this, and had to stop halfway through for a cake and ice cream break).
(A) Start with the inner lining facing upwards. (B) Fold diagonally in half, though make sure you can see a couple cm of the bottom half to prevent the inner lining from showing when the clutch bag is closed (in other words: not quite half). (C) Fold in the sides, so that the top and bottom halves are of equal length. (D) Stitch along the top of the fold, to make sure it stays in place. (E) Fold down the top fold, pin in place and stitch it up. (F) Attach the strap and sew in place the clip buttons. Yay, clutch bag done!
Have you sewed a clutch before? I love adding homemade items to my wardrobe. Let me know if you try making one of these!