I have some preserving jars I picked up from an op shop a while back that are gathering dust as they didn't come with lids. There are loads of tutorials for adding a simple fabric cover to a jam jar but I wanted to create a lid within the cover.
What you need:
Trace around the rim of your jar on the template plastic BUT when cutting, cut 3mm inside the line.
Find a round plate or lid that is approximately 5cm or 2 inches wider than jar. Trace and cut.
Trace around jar on felt. This time you need to trim 3mm outside of your line.
Add a little glue to the centre of your felt and add template plastic.
Add a small amount of glue to the margin outside of the template plastic. If you add to much it will show through your fabric
Press felt & template plastic into the centre of your fabric.
Add any bias or trims to the outside of your fabric. You could easily leave the pinking shear edge also
Measure your elastic length around the jar
Sew elastic together and pin to the cover. Mark half way on the elastic & also the cover with pins. This is just a gauge to evenly sew the elastic.
Set your machine to a zig zag stitch - quite long & wide. Stretch elastic evenly to your markers as you sew.