Cap screws filling with crud! Aaarg

Hello again, Has anyone come up with a solution to stop the heads of Allen screws/bolts from filling up with crud, especially those with heads facing upwards? It really is a PITA having to clean them out when needing to loosen/remove them, especially those that are in a counterbored hole and have the crud around the peripheral as well. Special plastic caps are available with spigots that push into the heads, but in lots of 1000s! Er, no thanks, I only need a handful. I could make something using hex or bar material and a disc of some material, but life is too short, but then again the crud in those cap heads really REALLY bugs me beyond belief. It did so on my V10P all those years ago, but never came up with a solution other than the usual small screwdriver/wire method of cleaning them out before being able to insert an Allen key. Any suggestions please? Regards Geoff - feels good to get hand oily again :-))