there are all kinds of animated knots on this site. Some are the traditional Celtic knots.

It is very hard to tie celtic knots in real string, as the knots have a lot of corners and open spaces that string will not keep.
You can tie the knots pinned down on a board and stiffen before you take it of, but that is not a guaranty that the knot stays in shape. And hemp is known to change colour dramatically when wet, and when treated with glue.

The only knottyer I know who ties celtic designs with success is using silver and gold, it is Loren Damewood, also known as Goldenknots, an example:
Main site, see galleries for more of his celtic work:

There is a book on the market which promises to use Celtic knots in jewelry, but they use basic Turks Head knots:
and other woven knots:
instead of beads.

Here is a link to a site where you can buy the book:

Sorry not to be able to help you further, but you have picked a hard one this time.
Feel free to contact me for more info or hints.

There is a website called animated knots by Grog. This site is very useful for knots of all types.

Okay here we go;

First here is a site that teaches knot tying

Here are some celtic knot patterns

And here is a Blog for celtic knot tying with useful links especially for celtic knot tying.

Good Luck and don’t get sore fingers!

check here

there are some books on that

and how to draw them