You can use the print out as it is or carry on and make a proper board. Cut art board to A4 size. Thin hardboard, ordinary card, or even thin plywood will do just as well. Apply glue to the board.

Stick the sheet down. If you're worried about coffee stains and so on then cover it with sticky back plastic or slip it into an A4 clear plastic sleeve (see this link). Cut Mastermind plastic pegs (or similar) for the counters. There's loads on Ebay. Six pieces for each team plus one for the ball.