TT Electronics Optek Technology has developed a power line design kit. Designated the OVPL5W3K, the kit includes FR4 PC boards populated with three 0.5-watt white LEDs, along with a wire harness with connector, and a hand insertion tool. 

The kit consists of five PC boards measuring 8x7/16in..

Each board features three 0.5W white LEDs with a viewing angle of 120 degrees, typical CCT of 5000K and typical luminous flux of 50lm per board at 15V (125mA per board).  Additional individual board assemblies are available (part number OPA733).

See http://www.optekinc.com