First I 3D printed my design on a resin printer to get the best detail. Then I made a silicone mold from that. Cold-casting is a technique where you mix an epoxy or polyurethane (I used polyurethane cause it cures much faster) casting resin with a metal powder to get a similar weight and luster of a specific metal. Then after the pieces are cast you need to use #0000 steel wool to polish them so they shine. As an alternative to metal powders which are expensive (~$15/lb), sand can be used to give a stone like grainy texture. I just added these cold-cast sets as an option on my etsy shop , but I made the design free to use so you could totally go and build your own casting setup if you have a 3D printer or use an online service to get some prints made.
The board is done with a laser engraver, but a wood burner and a piece of wood/leather/pleather/canvas/whatever and a ruler will work just as well to make a grid for a game board.
Today Hnefatafl was released for iOS. It offers offline (against human or AI) and online play (cross-platform). You can create your own variants (over 200.000 possibilities) or play one of the predefined ones.
The Android version (https://play.google.com/store/apps/details?id=com.fellhuhn.hnefatafl) is in review and should be available soon (currently only the old version is available). The Steam version (https://store.steampowered.com/app/1249510/Hnefatafl/) should be available by the end of April.