I have
LED's for moonlight in my Discus tank - i used a somehwat similar
DIY - but i used a waterproof LED strip in clear
PVC there are usually a number of them on ebay( i didn't want to have to coat in clear epoxy) and the one i bought the primary wiring was also enclosed that would be exposed to water from the tank and it came with a power supply. As to the parts, come up with a list that you specifically need and call your nearest eletrical store - the parts, including the power supply are common items.
And it's great look - but my plecos, when the plecos come out after the primary lights are off - i don't have to use a red light (falshlight) to watch them.