that one is a long board rocker table for 72 to 8 ft boards
its pretty flat
but adjustable
just stick a bit of wood under the nose and tail and weigh down the middle

i just use flat insulation sheet because its available around the corner
i would prefer to cut one out of solid and have a thicker base on it
really i have about 4 or 5 tables and they take up about 1 1/2 square meter standing in the corner
and theoretically i could bag 5 boards in succsession and they are adjustable with blocks and wedges.
if you want a really good adjustable design dave aka Craftee has a nifty one that is changes around a bit.
i would post it with his permission