Christ, I hope some of these suggestions are just to permit you to travel/visit in places that require a mask. I hope no one thinks pulling a Buff over their mouth is going to do anything much!
If you’re serious about preventing yourself from spreading a possible unidentified infection (good on you) try and find an N95 mask through a legitimate supplier, or something else that’s been proven through testing to limit the spread of viral infections (N95 are in critical supply).
One reason we’re not mandated to wear a mask everywhere, is that most would end up wearing some up-cycled tights, yet the false sense of security, corresponding lack of social distancing (and little-to-no protection) would likely just lead to an increase in avoidable infection. Even an N95 mask isn’t very effective without proper procedure (don’t adjust it, remove it to have a drink, single use etc!).
There’s tonnes of peer-reviewed research out there on this, but for reference an N95 mask can be 95-99% effective when used correctly, whereas homemade masks can be at 5% or even lower. https://pubs.acs.org/doi/abs/10.1021/acsnano.0c03252
If you simply want something to allow you access to a mask-only area, get something cheap and comfortable and practise social distancing.