Very handy! Gonna have to try a few of these. You know, if you're an arts and craft type, you can use them for projects too! I did one with my students called " Tye-Dye Butterflies " where you flatten the filter out, dampen it with water, then use a marker to create a pattern that spreads out. Let it fully dry, then fold it like an accordion, pinch in the middle and wrap with a few pipe cleaners to make the body and antennae.