How can I power 7 IL151 5mm Clear White LED leds for a sculpture in a series circuit?
simulate this circuit &ndash; Schematic created using CircuitLab

One thing that can be tried is 3 strips in parallel. First and second strip will have 2 LEDs and series resistors. Third strip can have three LEDs and series resistor. Then a 12 V supply would be sufficient. Sizing of resistors to be made accordingly.