A simple box is made from a plastic 35MM film container.
Hole in the bottom for lead exit and 2 holes in the removable top for sw./led mountings. This allows using the sw. for a terminal board and then just snap the top back on the container when wiring is done. [ If you use a clear film container , the led need not be mounted on the lid , as it can be seen in the clear can] .
Simple , fits in your hand nicely, with the sw. being ergo- operated w/thumb...
Also, if you go to RS , they now have a led with bulit-in resistor for 12 volt operation..
Part # 276-209.
Saves from going with the extra dropping resistor and extra wiring..