Doppeltree [1] and Pinyon [2] are both interesting hemp and cloth coffee filter options too. The biggest question is have hemp and cloth coffee filters been tested for food safety with hot water? I love the idea of a reusable travel filter. However I wonder if using a disposable filter that is certified as biodegradable is a better indicator for food safety? [1]: https://www.doppeltree.com/collections/ [2]: https://pinyonproducts.com/collections/all.