[Eman]

Buy some rare earth (neodymium) magnets. You'll be amazed how strong they are and they'll catch any and everything. I use small ones at the head drain back holes, larger ones in the lifter galley and large ones in the oil pan. I stick a couple on the oil filter too. The ones in the heads are generally covered in fine metal dust which i clean off whenever I adjust valves.
I ordered them on ebay but see that Home Depot had them last time I was there. Don't use refrigerator magnets, they're useless.