My Sketch

function setup() {

  createCanvas(800, 800);

  noLoop(); // Stops draw from looping

  stroke(0);

  noFill(); // No fill, so the inside of the rectangles remains empty

​

  let cols = 15; // Number of columns

  let rows = 20; // Number of rows

  let w = width / cols; // Width of each rectangle

  let h = height / rows; // Height of each rectangle

​

  for (let y = 0; y < rows; y++) {

    for (let x = 0; x < cols; x++) {

      let xPos = x * w + random(-10, 10); // Random offset for x position

      let yPos = y * h + random(-10, 10); // Random offset for y position

      let rectW = w * random(0.7, 1.2); // Random width variation

      let rectH = h * random(0.7, 1.2); // Random height variation

      rect(xPos, yPos, rectW, rectH); // Draw outer rectangle only

    }

  }

}