Spread a 1-inch-thick rectangle of coarse grout, using a trowel to measure 2 ft. wide and 4 ft. long onto a flat section of ground.
Place three rows of 12 bricks facing vertically onto the grout across the entire rectangle. Press the bricks halfway into the grout.
Spread another 1-inch-thick layer of grout over the top of the bricks, then place six rows of six bricks facing horizontally across the entire rectangle. Push the bricks halfway into the grout.
Repeat this process until the form is 2 ft. high.
Lay an 8-inch-wide section of 1-inch-thick grout along the right and left sides of the rectangle, then lay bricks horizontally along these sections.
Spread another 8-inch-wide section of 1-inch-thick grout on top of the horizontal bricks on the right and left sides, then place bricks vertically over the same section. Repeat until the right and left sides are each 1 ft. high.
Cover the entire brick seat with grout, then scrape off the excess using the trowel. This fills any empty areas with grout.
Allow the brick seat to dry for 48 hours before use.