Does any place sell replacement foam ring/donuts?

[Gatsby]

I have a few lights that could stand to have a new foam ring/donut to prevent battery rattle - does anyone know where there is a site that sells different size foam rings?

 

[kosPap]

and Idea I am toying with is using packing foam sheet to make a cylinder..and fix it with packing tape...

on the otehr hand just this morning I made 14-18mm battery adapters from external diam 19mm PVC pipe