To determine the thickness of aluminum strips, you can use a micrometer or a caliper, which are precise measuring tools. First, clean the strip to remove any dirt or debris. Then, place the strip between the jaws of the micrometer or caliper and take a reading. Ensure the strip is straight and not bent to get an accurate measurement. For strips with irregular edges, use a thickness gauge or a digital indicator to measure at multiple points to get an average thickness. Always take multiple readings to ensure accuracy and consistency.