Assuming you are in the US: The two best options I could find on Amazon are below:

https://www.amazon.com/YHYPY-Accessories-Handmade-Degree-%EF%BC%88White%EF%BC%89/dp/B087Q4PKSK/ref=sr_1_1?crid=17LZCTP8X355N&dchild=1&keywords=ash+catcher+14mm&qid=1589510591&sprefix=ash+catcher+%2Caps%2C1170&sr=8-1

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https://www.amazon.com/Handmade-Filter-Accessories-Bottle-Percolator/dp/B088DX1S44/ref=sr_1_2?crid=17LZCTP8X355N&dchild=1&keywords=ash+catcher+14mm&qid=1589510591&sprefix=ash+catcher+%2Caps%2C1170&sr=8-2