01. Circuit test
The First try didn't work. Then I used Arduino to find out the problems.
The problems are:
1) I used the wrong feet of the pushbutton.
2) I confused the “+” and "-" of the LED, and also used only one 1.5V AA battery to power the 3V LED.
Then I made the right circuit below.
02. Make a container
The original design was based on the metal plate and semi-transparent plastic. But I can't use SHOP to cut the metal now. So I tried to build it with the plastic and black tape.
However, the plastic is too crisp to crack, and I measured the whole size a little smaller than it should be. When I putted the batteries in it, the case couldn't fold very well and parts of the plastic broke off.
As a result, although the flashlight works good, the appearance is a disaster.
1) Making a neat appearance is way more difficult than making things work.
2) There are lots of accidents about materials. Try it first before you choose it, and keep yourself a bunch of backup plans.
3) When I tested the circuit, sometimes the wire went very hot, sometimes the LED flashed then dead. So check the elements' parameters first to prevent danger.