Two-tone, three-tone or four-tone pastry can be made up using the techniques mentioned elsewhere in my blog. In the case of a cross-laminated single colour, for example, a chocolate croissant dough is made using coloured butter and a smaller number of layers the 3-3-3 system. The pastry is then frozen in a block, and when semi-hard, it is sliced into strips, and the strips are placed facing up on top of a chilled plain croissant block of dough until the dough is entirely covered. The block of pastry is then sheeted, ensuring that the layers on the top of the block are stretched to elongate them and not widen the layers as this will lose the effect of cross lamination.
Full recipes and further tips are available in my book, The Art of Lamination: Advanced Technical Laminated Pastry Production.