They were made using crossed laths, horizontal at the front and vertical at the back, held together be decorative stitching using strips of flax or grass. Two women worked together, one at the front of the panel, one at the back, and the strips of flax were "stitched" through the gaps between the laths to create the cross stitch patterns.
The patterns all have spiritual meanings.
In Te Papa, the National Museum of new Zealand in Wellington, there are some modern interpretations of tukutuku panels, using traditional techniques, but non-traditional colours. No photography allowed I'm afraid.
At the Art Gallery in Christchurch, we were lucky enough to see an exhibition of cloaks and baskets by contemporary Maori weavers/artists. The exhibition was called The Eternal Thread and has been to the US. It was really inspiring, particularly the cloaks, but once again no pictures I'm afraid.