[timytamy]

This year you should be fine with straight onto aluminium. The thing that you need to watch out for is "grounding" (and energising) the frame. This happens when there is an electrical connection between any cables/terminals, and your robot frame.

A quick educational test you can do is to get a multimeter and check for continuity between the cables/terminals on your components, and their casings (the surface that will press against the aluminium). If the multimeter shows anything smaller than 10kohm than you will need to place something non-conductive between the frame and the component (Hint: everything should be already ok). This is also the same test they will do at competition.