I painted cars for twenty + years so I thought I would share a tip .
tin foil works very well for masking dirty parts ( engine parts , hoses , greasy shafts ) or parts you are scared to tape on ( stuff the tape may peel off )
the coolest thing is that you can wrap it and squish it and it stays .
if you get it tight enough and strait enough you can get a pretty clean line .
works great for wiring harnesses and chains .
you can put a clean rag under it if you are painting something you are worried about scratching
heavy duty foil is the best but any will work ( it just likes to tear easy )
be careful using a bunch of small pieces . you want enough on each end to squish together , it doesnt hurt to throw a piece of tape at it eather
hope this is helpful to someone