How to Build Copper Buttons and Weighted Pressure Plates
Copper Buttons
Craft a Copper Button from copper ingots using a crafting recipe. Place it on any solid block face. Pressing it emits a short redstone pulse, just like a stone button. Copper Buttons oxidize over time through the Exposed, Weathered and Oxidized stages, matching the copper block stages.
Weighted Pressure Plates
Craft a Medium Weighted Pressure Plate from copper ingots. Place it flat on the ground. It emits a redstone signal whose strength scales with the number of entities standing on it, similar to a weighted pressure plate. Use it to detect how many mobs or players are on a platform.
Oxidation Stages
As copper oxidizes, the button or plate changes to Exposed Copper Button, Weathered Copper Button, then Oxidized Copper Button. The same progression applies to the plates: Exposed Medium Weighted Pressure Plate, Weathered Medium Weighted Pressure Plate, Oxidized Medium Weighted Pressure Plate. Each stage is a separate block in the registry, so you can place any stage directly if you have it.
Stopping Oxidation with Wax
Apply wax to lock a stage in place. The waxed variants are Waxed Copper Button, Waxed Exposed Copper Button, Waxed Weathered Copper Button and Waxed Oxidized Copper Button. The plate equivalents are Waxed Medium Weighted Pressure Plate, Waxed Exposed Medium Weighted Pressure Plate, Waxed Weathered Medium Weighted Pressure Plate and Waxed Oxidized Medium Weighted Pressure Plate. Waxed blocks never advance to the next oxidation stage, so use them when you want a fixed appearance.