How do I create a Damask pattern in illustrator?

For the damask or roccoco patterns you need to draw the whole element (because it is not entirely symmetrical) using the pen tool, you then need to use the transform option to move the elements a precise amount (the amount is up to you, keep it a whole number if you value your sanity), having positioned five, one in the centre and four around it, you need to draw a rectangle which runs from the centre of each of the four surrounding elements – this will define your pattern and must be precise otherwise the pattern will not meet accurately – once you have everything positioned and coloured as you want select all elements (with the rectangle at the front) and Define Pattern under Edit then check it works by filling a rectangle with the pattern (there will appear to be slight separations at various viewing scales, zoom right in to check them – if you have done it right there will be a smooth join).