The full Hnefatafl needs a 11x11 grid, which you can make with the full 6x6 Green Box tile grid if you play on the center points and the points in the intersections between the tiles. The black player needs 24 pawns, so use blue cubes with a few green added. The white player needs 8 pawns and a king, so use yellow and red respectively.

The smaller Tafl variants listen on Wikipedia are easier to compose.