i have made some fabric ones too. using this easy non-sew washable way.
as for filters to slip inside the fabric, can use paper towels, hepa vacuum bags, coffee filters,or even just extra fabric in front of the nose area. i wash the fabric mask after each use and throw the filter away. someone suggested boiling the mask instead of having to run the washing machine each time.
i am hanging on to my used surgical masks just in case they become reusable after a waiting period.