How to String the LEDs?
Colored String lights commonly used during festive occasions or parties greatly help to enhance the mood and the ambiance. They also look pretty attractive and catchy. If you desire to use the present circuit for decoration purpose, you will need to connect the LEDs together through flexible wires so that they may be hung or attached or oriented anywhere as one wishes. The connection is made as follows:
Since the forward voltage drop of colored LEDs is around 2 volts, the supply voltage of 4.5 volts can be a bit too much for them to tolerate. Series resistors connected to each of the LED will restrict the current and light them up safely.
Connecting the resistors to the LED leads themself would interfere with the flexibility of the LEDs and hamper the string effect; therefore, fixing the resistors over the circuit board and connecting just the wires to the LED string from the PCB would be much cleaner and more reliable.
As shown in the figure alongside (click to enlarge), begin by interconnecting the LEDs together using small lengths of good quality flexible wires as illustrated.
Seal and cover the wire joint at the base of each LED using RTV silicone glue. Let it dry for a few hours until it solidifies.
In view of safeguarding the LED string from dust, moisture and mechanical shocks, it would be important to enclose it in some kind of flexible and transparent housing.
The tubes used in bikes for transferring petrol from the tank to the engine is perhaps best suited for the purpose, or any other type of PVC pipe will also do as per your own choice. Insert the whole LED string into the procured tubing appropriately without breaking the wiring and allowing only the connecting wires to come out from one end of the tube. Seal the other end using two-compound glue.