Save your egg shells until they are dried out (microwave if you are in a hurry) and give them a quick buzz in the blender or food processor. This should give you a gritty powder that will hurt the slugs, thereby discouraging them from going wherever they find it. Diatomaceous earth would also work (probably better, but that's be a purchase instead of a freebie). Dust the plants with either and circle them with a large fat ring of the powder.
My grandma would have said to put out beer traps, but my understanding is that such traps need to be situated well enough to drown the slugs because otherwise they will escape.
Edit: here you go! https://www.learningwithexperts.com/gardening/blog/organic-slugs-snails-control