You can buy the led chain in any store. 

I think it is also possible, with any slicer, to modify the dimensions in order to also accommodate LED chains with a greater number of lights. 

Once the LEDs have been inserted, just glue the two printed parts. In this case I used a semi-transparent blue petg 0.2 resolution 

You can find all my models here, thank you who will appreciate with a download or with a like