Build the bed on a raised platform of bamboo or bricks in a shaded, closed shed, never on bare soil. Lay the first layer of bundles side by side, then the next layer across them, so the bed stays firm. DMR lists bed sizes of 100 by 100 by 100 cm, 60 by 60 by 30 cm and 60 by 60 by 120 cm.
Break the spawn into small pieces. Place them along the edges of every layer, 5 cm apart, leaving a margin of 12 to 15 cm from the edge. DMR uses 500 g of spawn and 150 g of red gram (arhar) powder for a 30 to 40 kg bed; the powder is a nitrogen supplement dusted over the spawn. Press the finished bed down from the top.