I use Ki-Cad free open source to make strips. I just make the LED component footprint then wrote an app to place the LED footprints on the PCB. All the design files are text based so they're easy to create/edit with any programming language. I used a PHP to create the PCB.
I just input the number of LEDs, the XY location of the first LED, distance between each LED and milliseconds later the PCB is done.
The foot prints I made for the LED will accommodate both Cree XP, and OSRAM Olson SSL.
I made similar foot prints (one for each string) with the component "pins" offset from one another so the routing of the tracks was very compact. I can fit one row of four strings with mounting holes for a heatsink on a 0.35" wide strip.
There is a copper fill across the screw holes which are also connected to the thermal pad. This make a pure copper thermal path to the heatsink.
For 2.1v red I place 21 LEDs per strip for white and 2.8v blue 16, so the forward voltages workout to about the same forward voltage per string. The string Vf would be just under 45v with leaves enough headroom for a simple buck CC driver powered with 48v.
This strip has 4 strings per strip.
The red solder paste pads is where the LEDs are placed.
