You need these leds for it:

https://www.amazon.de/dp/B07C1PQMNC?psc=1&ref=ppx_yo2ov_dt_b_product_details

This battery holder:

https://www.amazon.de/dp/B07MQ9DNP6?psc=1&ref=ppx_yo2ov_dt_b_product_details

this battery:

https://amzn.eu/d/eHQB3qD

and this switch:

https://www.amazon.de/dp/B0BD39FPRQ?psc=1&ref=ppx_yo2ov_dt_b_product_details

Step 1:
Glue the lamp to the lamp holder so that the holes are directly above each other.

Step 2:
You take 5 Led lamps and cut the cable and lead the cable through the hole down to the battery

Step 3:
Push the switch into the side of the battery compartment.

Step 4:
solder one cable from the Led lamps to the switch and the other cable to the battery holder. Finally, connect one cable to the switch and the battery holder.

Step 5:
Finally, glue the rear panel in place.

you can see the assembly at tiktok

https://vm.tiktok.com/ZGeHAy8Mg/