Step 1. Obtain fabric. I chose an used thin cotton towel, but of course you can also buy a new soft fabric.

 Step 2. Cut out your circles. I made the rounds in the size of the jar, I will keep them there.

 Step 3. I used a blanket stich to fix edges.  

 And, that's it! They can now be stacked up in my bathroom to replace my old disposables. Washed with my other whites in the washingbag, they'll last for years. It will save not only nature, but it will be also some small saving for my bank account.