My diesel Bongo (as diesels do) has a good steady vibration at tickover, and this will tend to expose any loose and rattle prone items. For some time I'd had an annoying rattle from the drivers door when on tickover, so I thought I'd investigate. I removed the drivers door card. This is not difficult - after undoing the various screws, including the less obvious ones in the door pull recess and the one hidden by the door opening handle, you just need to twist and ease the door opening assembly through the door card and then disconnect the the window switch from the harness by depressing the plastic catch on the plug and pulling the connector apart. Having removed the door card, you need to peel back the polythene membrane that protects the interior of the door. This is held on by horrible black goo but you don't want to lose or compromise this polythene membrane by cutting into it. The membrane can be peeled back without upsetting or displacing the black goo if you use a sharp kitchen knife and use a sawing action on it while peeling back the membrane. This is best done in cooler weather when the goo is less sticky. This will leave a bead of goo on both the membrane and the door and these will re-bond as soon as you press the membrane back in place. Having peeled back the membrane so that I could access and inspect the door interior, I discovered that the metal stiffener that runs top to bottom in the middle of metal exterior door panel had de-bonded from panel. It seems at manufacture to have been attached to it at intervals by some kind of adhesive. This had cracked and although it still held the stiffener captive, it allowed it to rattle. I could have tried securing it with some 5 minute epoxy but I was short on time, and really it wasn't necessary. The solution was simple - I got some suitable foam material (the sort of squidgy but firm polythene cell packing that is used to protect many boxed electrical items) and packed it in between the stiffener and the panel. Rattle cured
I've had to fix one or two other similar rattles and it always amazes me how much it makes a car feel new again. Thinks like worn droplinks and anti roll bar bushes, and rattles in the bodywork, really make you feel like you're driving an old banger rather than a taut and quiet new car. Well worth attending to these mundane jobs - I'm really glad I did 
