Surfing the interwebs for hnefatafl-related stuff, I stumbled across SevenOaksGrove on Etsy. Among lots of other things, it offered a very nice vinyl hnefatafl board, allowing the playing of 7 x 7, 9 x 9, and 11 x 11 versions. The price was really decent, especially given the postage from the US, so needless to say I ordered a board plus a set of playing pieces.