My sister lives in Pittsburgh and I'm trying to help get an air filter for the wildfire smoke. She's just trying to buy a cheap (probably useless) one off of Amazon but I'm trying to talk her into making a corsi Rosenthal box. I sent her the instructions from https://corsirosenthalfoundation.org/instructions/ but she's so used to just ordering garbage off Amazon this might be a bit much for her. Is anybody selling in an in expensive kit? Or something similar?