Review on 📌 60 Piece Pack of Self-Adhesive Cork Squares - 3.74x3.74 Inches Mini Backing Tiles Sheets for Coasters, DIY Crafts, Walls - 0.04 Inch Thickness by Kelsey Brown

They're flimsy, although that's usually what you want when it comes to gluing things like the bottoms of coasters. We are prepared for this because we 3D print many coasters here. This and other office-related items (pen holders, etc.). So far they seem to be holding up and offer just enough coverage and the protection you would expect. The sticky side seems to hold too. We thought about it when we came across options that started peeling off within a few days. So far we have not encountered this. However, we will update if we find otherwise. It's also a fair amount of coaster for the price.