While working on the 3D printed battery cover for IS33, I thought to myself: “I really don’t know if my cheap ass digital calipers are that accurate”. The little tabs that holds the lid in place are less than 1.0mm thick. So, I designed a simple calibration block with steppings at 1″, 3/4″, 1/2″ and 1/4″. Turns out my caliper is plenty good for my purposes. This block of plastic cost me ~$16 at the time. WAY cheaper than getting actual gauge blocks. It’ll at least give me a rough idea if the measurement readings are sane or not.