Step 1: The limited work area
I've placed two rulers in the picture to give a sense of size.
Step 2: Filling the space
In this picture I'm playing around with an Arduino Lilypad. If i need this space for something else I can easily pick up the tray without everything on it and place it elsewhere within having to dismantle stuff.
Step 3: Reusing the space
Note that when moving and storing a tray I often need to do some stacking, which I'l unstack when actually using the tray contents. But I do manage to avoid having to individually relocate dozens of pieces.