All the websites and books I have looked at on Zentangle seem to use the Sakura micron pens. I started out using these but found replacements difficult to come by locally so decided to look at other pens. I always loved my Rotring ink drawing pen but I found the nib too broad for the intricate nature of the patterns I was trying to create with Zentangle. After a bit of research I got myself a college started set of Rotring Isograph pens and they are fantastic. I have been using the .25 one for drawing most of my tangles and the .50 for the filling in. They give a lovely strong black and flow well over the paper. They were well worth the investment as far as I am concerned.
When I did A level art, coloured pencils was my favourite media so have always had a selection of different colours. I did try combining coloured pencil with my tangles but wasn't as happy with them as the monotone as I felt it detracted slightly from the nature of the pattern (see the coloured one that I have added to this post). I came across the Derwent Graphitint range of pencils and am enjoying playing with them. They are like working with a coloured pencil but the colour is just a slight hint, basically a tinted graphite. I have used the "ivy" one here on a monotangle (using just one tangle), the colour is quite subtle and I am pleased with the result.
Whilst searching the internet I came across a Zentange Weekly Challenge. This week the challenge set was for everyone to use the same string which split the tile into eighths and resembled the fortune tellers that I remember making as a child. 
