You already know that I hope you will never take out slugs by serving them a dish of beer.  Actually, slugs are a valuable food source for many birds and animals.  They do serve a useful purpose, and a short physical barrier will keep them out of, well, whatever.  Stilll, I couldn't resist doing a "cute cat pic" cartoon with them.  It goes with the one you will see in a few days, with a human subject.