Step 6:

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And here's the rack from a couple of angles.  I didn't have any countersunk self-tappers, so the screws are proud.  I've added a couple of spacers (rubber grommets, steel washers - anything will do) to the mounting screws to give some clearance.

There are all sorts of permutations to a gadget like this.  The main thing is to use what you have to hand.