How to make this banner
Cut out your triangles of fabric with even edges of 23cm. I made a pattern with paper to cut around. Cut two triangles for each flag. Sew on two sides and press seams flat. Turn right side out and press again. Sew as many flags as you need to span your room. To attach the flags together to form a banner I used white webbing (you could also use bias binding). Fold in half and press down the centre. Push the rough side of your flags inside the fold of webbing and pin. Leave about 15cm of webbing on either side of your banner ends. I then tacked all the flags into the webbing and machine sewed along the webbing about 1.5mm in from the flag edge. Unpick all your tacking. Sew a loop on each end to attach to hooks in your room.
Let me know if you make a banner using this pattern. I would love to hear about it!