I'm not sure what you're asking, Are you planning to hand make some custom tail lights?
Three parts to this.
1. fabrication of the light cluster itself, you could probably 3D print something if you have a big enough printer and you're handy in CAD, you would need to be able to replicate the two sides exactly as any difference would be obvious when lit up.
2. The LEDs you use would need to be carefully selected to make sure they give enough light output for what you want. For example the brake lights need to be much brighter than the normal tail lights, as do the fog lights and the indicators. they would also need to keep their colour, some cheap but bright LEDS might look red up close but as you move away the colour might get washed out. and look nearly white or just not red enough.
3. The wiring is very easy. The more complicated part is that the LEDs would either need to be 12V or have matched resistors to stop them burning out. you would also need to have some sort of low ohms resistors shorted between live and ground, to make sure that enough current was being used to keep the bulb failure unit from thinking the tail lights are blown.
You'll need your calculator and a good grasp of ohms law.