What you need10 cm wide fabric and 40 cm in length
Elastic around 10 mm wide x around 30 cm.
Start by sewing your piece of fabric into a long tube, either use a sewing machine or sew it by hand.
The length of your elastic will depend on it’s elasticity but 30 cm’s is a good starting point.
Securely sew one end of your piece of elastic to the inside of your tube (at one end). Secure it by double sewing it.
Turn your tube back the right way so your elastic is hidden inside if it isn’t already.
Pulling the elastic tight, pull it all the way back around to the other end and once again secure to the other end, on top of the place where you secured the elastic to start with.
Do not sew the fabric down at this last side as you will use that to pull across and cover up the stitching.
Finish up by sewing a strong seam over both elastic joints.