One of my favourite tools of the moment is my rivet nut tool. It's not expensive and looks like this: and you can pick them up pretty cheaply off eBay. What they do is the fix a rivet nut - again you can buy a bag of these cheaply - into a hole drilled in sheet material (e.g. 1.5mm aluminium sheet) and the result is pretty much a flush surface on one side and a post on the other, the post is internally theaded all the way through. So, so what? Well on the one hand this can give you a large secure threaded hole, but on the other side (literally) a good secure internally threaded post. I.e. an instant PCB standoff that is fixed very securely to your sheet material. In this way you can quite simply make a really great diy aluminium motherboard tray. Another use I am putting these to is in my own ATX and mATX IO brackets to give a really secure mount point for PCI-e cards. It's a great little addition to your toolbox that you'll find a ton of uses for.