Nevertheless, I would recommend that the circuit should be made in safer way and in a better enclosure (Perhaps a 3DP one – then battery contacts can be taken from a discarded 9V battery or a 9V ...

The battery pack and the output contacts are attached to the circuit board with decent wires in silicone insulation. Also, there are soft spacer sheets between the cells themselves, the circuit board, ...

All you do is press the Snap onto the top of a regular battery, and you've got a working single-LED flashlight. Not going to light up the moon with that, but kids will love it and they'd be handy ...