Here is a taster of my current project.
There are two separate assemblies here.
On the right is a simple soft latch arrangement that lights a LED.
The transistor looking component is actual a thyristor and the long silver component is a reed switch.
The thyristor is different from a standard transistor; when voltage is applied to the base briefly, the flow between anode an cathode will stay latched even when the base voltage is removed.
The reed switch is used to deliver the current to the base. Bringing a magnet near the reed switch will be enough to switch on the LED and it will stay on.
On the left we have a coil that uses induction to light the LED when it is brought into close proximity.
More details to come as I progress!