For the sake of knowledge, I'd like to ask few questions. Although not now, I'm thinking of building my own cheap tensile testing machine that isn't used for testing on ones with such heavy loads like commercial machine. 1. For the uper body, I'm just planning to start by connecting with extrusions but when buliding the machines, what materials should each parts be made out of to keep the machine stable? Could I get detailed information of why such materials should be chosen? 2. Any other things I need to consider when approaching such project?