Reddit mentions of Tesa Wire Loom Harness Tape Used By Mercedes BMW VW Audi

Though you're right, it's still not the right stuff to use. You want Wire loom Cloth Tape. It's the shit they use from the factory on wire harnesses.

https://www.amazon.com/Tesa-Wire-Loom-Harness-Mercedes/dp/B00EH6IZ6Y

Sorry about that. I didn’t know they made various kinds. Here’s an Amazon link where I got mine:

Tesa Wire Loom Tape

You can buy a wire harness these days.

Race versions won't include provisions for turn signals, a stereo, or, a legit accessory position; that won't power the full pump and ignition system, especially important if you run a points style ignition (cause you're not only draining the battery a hair quicker, but now you risk burning up your points).

As for making your own, that's going to depend on your application.

Boats will need a power and a ground wire ran for all accessories. You can reduce the ground wire count by using a distribution block. Power will be run to a switch from the battery, to a fuse block, then to the device, then to the distribution block, back to the battery, completing the circuit. A large fuse, circuit breaker, or a cut off switch is recommended.

For a car, things get a little more complicated. You generally want a clutch/neutral safety cut off switch, reverse lights, brake lights, and more. It gets more complicated because the brakes are powered full time along with the lights, but your signal lights aren't. This can cause back feed issues when the lights are on and you signal or brake. Diodes are one option, multiple bulbs/dual filament bulbs are another. High draw circuits are controlled by relays so you can use smaller switches and less fuses. The circuits are usually completed to a chassis ground. Ensure all your ground connections are free from paint and rust.

The best place to get a good visual is your local library. Check out ohms law to get an idea on how thick of a wire you'll need so you don't burn your car down or run an extra 200 pounds of wire.

If you have the old harness, it's a lot easier. Take it out complete. Lay it down on a few 4*8 sheets of board. Unwrap all the conduit and connect the dots. Automotive connectors are usually unique, so they only fit that one plug on the car. The exception to that rules is for light bulbs, though the socket around the bulb might be different.

Good luck. LPT: Don't pull the electric tape to break it, cut it off clean without stretching it so it's less likely to unravel. Use high heat conduit under the hood to protect wires. Wire loom tape is ideal for wrapping multiple wires and is a way better option than electric tape.

Tesa tape if you want it to look OEM.

Nice write up. But I have a few suggestions.

Instead of electrical tape you should use actual loom tape next time, the electrical tape will start to degrade over time.
http://www.amazon.com/Tesa-Black-High-Harness-Mercedes/dp/B00EH6IZ6Y

Generally using a relay, like in the diagram linked below will increase your light output and make your setup safer as the load isn't being carried by the switch.
http://www.offroaders.com/info/tech-corner/reading/relay-diagram.gif

Also, you should look into this type of connector for the battery end. You can slip it on under the nut on the battery connector and then use the screw to secure the power wire for your lights.
http://www.amazon.com/Panduit-ML8-CY-Barrel-Straight-Tongue/dp/B00B5P3KT2/ref=sr_1_49?ie=UTF8&qid=1414773726&sr=8-49&keywords=post+and+tap+connector

For wiring harnesses Im about to blow your mind:

Tesa Tape, use what the OEM's use.... No Brainer: http://www.amazon.com/Tesa-Black-High-Harness-Mercedes/dp/B00EH6IZ6Y/ref=sr_1_1?ie=UTF8&qid=1414157204&sr=8-1&keywords=tesa+tape

Solder and Heat shrink for connections of course.

Oh here is something: http://www.amazon.com/Tesa-Black-High-Harness-Mercedes/dp/B00EH6IZ6Y