One of the other things I've been wanting for a long time is a covered, lockable storage box for bicycling around town. I have Givi cases for my motorcycles, and I find it indispensable to be able to store things securely while away from the vehicle. It's something I miss when biking.
So, I went to my local hardware store and found this small-ish plastic toolbox for about $15.
The first thing noticed is that the lid doesn't stay up on it's own. Very annoying.
The culprit turned out to be these plastic tabs intentionally appended to the hinges. What the hell? So, I shaved those off with a wood rasp, and now the lid will at least stay open when the box is level. But I may need to revisit that down the road.
So, on to the mounting. The Idea I came up with was to put key-hole slots into a plate, so that #6 sheet metal screws could be inserted, the whole box would then slide to lock the screws in place, and then the screws tightened down. The idea is that this way, it'll be easy to remove the box when necesary, but you have to be able open the box to remove it from the bike rack.
The nice thing about this particular project, is that it's its own storage own box :)