Make this armrest organizer for a sofa through this wonderful tutorial byEstadistica Datos del Mundoon Youtube.
The length should be 33.5 inches.
Step 2:
Paste the thin thermo-adhesive wadding.

Image by Estadistica Datos del Mundo
Make a mark every 2.9 inches on the shorter side, then draw lines.
Step 3:
Place wadding with the reverse of cotton fabric.
Secure with pins, then sew on the lines.

Press with an iron.
Mark the center and make a line.
From the center, mark 3.5 from each side of the line, then draw lines.

Pass a backstitch along the lines.
Then sew on one edge.
Flip the cotton fabric on the other side, then mark the center.
After that mark 4.72 from the center and draw the lines.
Pass a backstitch and sew along the lines.
Step 6:
Join the front to the back in the center.
Sew along the seams.
Step 7:
Place it on the long cotton fabric with wadding, then sew.
Do zigzag stitching all around the long fabric.
Step 8:
Fold the bias in half and iron.
Sew it all around.
In the corners, fold the bias.