Hi there! A few words of advice...

First, anyone underthe sun can design a new tartan and decide to call it "NC MacLeod." But it would mean absolutely nothing. If you want your tartan to be official, you need to get approval by the chief of the clan. I'd also reccomend getting it approved by the NC branch of the clan, as this tartan will be used specifically for them.

When you are ready to have it recorded, you can submit it to the Tartans Authority directly via their web site, which Rocky already posted a link to. They also have an article there about the recording process that would be very helpful for you to read.

But that's putting the cart before the horse. You need to actually come up with a tartan design first.

Here is what I would do: First bring the idea up to the Clan Society here in NC, to see if there is any interest in it. Second, start coming up with designs, and also let the clan cheif know what is going on and get his input. Once you've come up with a few designs, you can select a final one by any number of means -- either have a committee, a vote, or let the cheif select. It's up to how you want to do things.

As far as the design itself goes, the first thing I would do is to study all of the pre-existing Clan MacLeod tartans. You can use the Tartans Authority web site to begin this, but you may also want some more detailed information. Ruariadh MacLeod (first cousin to the chief) is a tartan expert, and he has written a fine little book on the MacLeod tartans. I beleive I still have one or two in stock in our museum gift shop (I can check this morning when I go in). It's only a few dollars, and well worth it for MacLeod tartan enthusiasts.

I say to study the pre-existing MacLeod tartans because, as you obviously intend this to be used as a clan tartan, you will want to highlight the fact that this tartan is a MacLeod. You want it to be based in the MacLeod heritage, rather than something new created wholecloth. So a likely course of action would be to take a preexisting MacLeod tartan, and change a color, or add a color. Or maybe combine elements of more than one macLeod tartan to create a new design. Or maybe combine a MacLeod and the Carolina tartan. You get the general idea. But my reccomendation is to start with the MacLeod tartans themselves and use them as your starting point for a new design.

Good luck with it all! And if you need any advice along the way, please let me know.
Aye,
Matt