As the title suggests, I'm new to Blender and 3d printing. What I need is very simple, unfortunately the learning curve for modeling applications is a bit daunting. I really just need a flat rectangle about 10mm thick and 10mm wide by 200mm long with 16 circular holes measuring 6.5mm in diameter. I realize to get there I need to master the interface and get acquainted with basic modeling. I also need to figure out how to set Blender up to do measurements in mm rather than BU. Any suggestions?