A Must Have Tool for every Aircraft Builder - HomebuiltHELP Watch in HD on YouTube! Share on Facebook! The digital caliper is not only now inexpensive but also an extremely useful tool for experimental aircraft builders. This video demonstrates how to use the caliper for measuring materials and hardware used while building an aircraft. A quick review of basic features and where to buy is also shown. Stainless Steel Electronic Digital Caliper: http://amzn.to/2FJWx5t