Walmart sells them in the craft section near the decorative beads. They're 2 in diameter 3/4 in tall stackable clear plastic trays for storing beads, buttons or little sewing bits. Came in a four pack
We trap slugs in little bead dishes using the cheapest beer we could find. Slugs love beer. They get drunk and drown. Drain the beer off in the morning--the chicks love marinated slug.