Best Materials for Raised Garden Beds

Good stuff!

Treated wood hasn't contained arsenic for many years.

I'm curious do you know which material that snails don't like to crawl on? This summer I tried to put one little salad pot on top of a defect chair in the middle of my garden. Till now it has been 2 weeks in and the salad is still there and growing. I'm amazed & 'd like to find out what exact material of the chair legs...i'm searching the whole internet for hours but none mentioned the materials that snails don't like to crawl up. If you know please help share