ok im relatively new to hookahs but i am very familiar with the concept of a diffuser. ive looked around all over these forums and honestly, all the diffuser ideas on here seem like way too much hassle (yes, even the bottle cap). so i havent actually tried this myself, but i am fairly certain it will work - rubber band and a clean piece of cloth. cloth has tons of little holes in it, and if you use a rubber band to hold it onto the bottom of the down stem (like a little cloth bag) the smoke will travel through those little holes. if ya need more pull through, use a bigger bag of cloth at the end of the stem, or a thinner, lighter cloth may work better. who knows really, just an idea. i mean, basically no work, washed clean cloth is not toxic i think (though at that point in the hookah system i doubt toxicity under heat is a big issue) and its cheap. after using it you can wash it so it doesnt get nasty from soaking in water (nobody likes moldy smoke). ill be trying this as soon as i get some more shisha and coals (should be just a few days), and when i do ill let you guys know how it works. also if you have a wide base on your hookah like me (mya qt) and are willing to put just slightly more effort into a diffuser, some flexible hose capped off at the end and riddled with hose could be coiled around the bottom of the base and attached to the bottom of the downstem. just another idea, not planning on trying it out myself but if ya read this feel free to try it and let me know how it works p.s. this is my first post and im not massively knowledgeable about diy hookah stuff so lemme know if i wrote anything dumb peace out