Minecraft wiki entry for Command_blocks_and_functions, associated text: Pressure plates only blend in with only gold, iron, stone, and wood planks, but cannot be concealed in any other floor; command blocks can be used instead. Pressure plates can be replaced with a command block by using the if argument in the command /execute with a range and a clock circuit. The command /execute if @p[distance=..2] will test to see if any players are within a range of 2 (the command block itself plus 2 more blocks in every direction). Range 2 is the range a player want for a command block under a floor. Keep in mind that it will produce a globe shaped trigger area (rather than a cube), so a range of 2 makes an approximately 5×5×5 area and a range of 1 makes a 3×3×3 area (more like a + pattern with an extra block above and below the center). The player can get around this by using the dx, dy and dz arguments.