I remember an article from a back issue of Mother Earth News that described a homemade filter - essentially three or four rolls of toilet paper - unwound and then rewound tighter around a spindle (sequentially along the length, so the filter was nearly two feet long) and stuffed inside a tube for a tight fit. The reclaimed oil was in a five-gallon bucket above the filter, warmed by an incandescent bulb, and allowed to drip slowly down onto the filter media. Eventually it made it all the way through and what came out was pretty good. They sent it to a testing lab and the lab declared it good enough to use in an engine.
Typical of MEN articles of the time, the whole description was pretty breathless and a bit on the credulous side, but I didn't see anything too far out of expectation with it. It just didn't seem like a worthwhile use of money, space or materials to me at the time so I never went anywhere with it. If you're generating a lot of waste oil however, and have a use for second-run oil that tests good, then such a contraption could pay off for you, especially if your use of the resulting filtered oil would be a once-through application like bar oil.
[edit]
Ha! Found it:
https://www.motherearthnews.com/diy/...l-zmaz81jfzraw