I am fine on electronics construction, but not having any engineering experience, I need advice on construction materials. Bear in mind that I only have basic handtools, including minidrill, hacksaw and the like. There are a number of items I want to be able to fabricate myself (from sheet materials where possible). I am not concerned about things lasting forever, ease of cutting/shaping and reasonable strength are more important. For example a future project is likely to be an arm.