Electrical - Light String
https://smile.amazon.com/gp/product/B0757KHM56/ref=ox_sc_act_title_1?smid=A1332HU59Q57NY&psc=1 $65.44 + tax for 2 strings - 18 bulb holders
https://www.costco.com/Feit-48%27-LED-Filament-String-Light-Set.product.100405061.html 24 low power filament LED bulbs in string for $40 + tax - 24 bulb holders
Outdoor String Lights by Deneve - Heavy Duty Hanging Market Patio Cafe Pergola Rope String Backyard Lights Pro Weatherproof Commercial Quality Bistro Umbrella Festoon Garden Lights 48 Feet Long (Bulbs Not Included)
https://smile.amazon.com/gp/product/B00J4CUO3S/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A2L77EE7U53NWQ $33.08 + tax
Search on Amazon for "Light string".
Use 1" conduit clamps to mount each bulb socket to wood.