Cheap diffuser for sugar+yeast method. All you need is those cigarette filters. Make sure to remove the paper covering the filter you just need the spongy part to cram into the diffuser. If your print is not air tight just use silicone glue to seal the leakage. The top part fits those 4mm (ID) hoses. I use silicone hoses so since pvc feels a bit loose but shouldn't be a problem if you use ptfe tape. Also remember to buy the plain filters not menthol types. I'm sure there's other things you can just cram in there to get the same effect like cotton or a small twig.