The phrase "a flat base of" is correct and usable in written English.
It can be used to describe a surface or foundation that is even and level, often in contexts related to construction, design, or physical objects.
Example: "The sculpture was designed to rest on a flat base of marble to ensure stability."
Alternatives: "an even foundation of" or "a level surface of".
This was because crossbow bolts were short and heavy, with a flat base to absorb the initial impact of the string.
They are stretched over a narrow and slightly convex sound board, usually made of paulownia wood (Sterculia plantanifolia); the underside of the sound board is closed by a flat base, usually made of zi (Chinese catalpa, Catalpa kaempferi).
Acrylic courts are made of a solid, flat base of concrete or asphalt, layered with a shock pad of crushed rubber, sometimes from old tires or ground-up tennis balls, then topped with one or more layers of acrylic paint mixed with sand.
We already have an hourglass economy, with plenty of room at the top for those with existing wealth and access to capital, and a wide, flat base of lower-paid jobs that cannot be automated.
When achieving critical extraction, a flat base appeared in the subsidence basin of which the range was larger than the general ones.
Diploids often appeared bulb-shaped, with a rounded apical tip and a flat base defined by the cell's site of budding from its mother.
A pan with a flat base may also be used in place of the griddle.
Loosening of the tibial component was defined as a change in position of the flat base of the component in relation to the long axis of the tibia by >2° or a progressive radiolucency > 2 mm.
Moreover, while the flat base of Minié's projectile was deformed against the pillar as in Thouvenin's weapon, the rest of the bullet maintained its shape and accuracy.
Dashed line marks the postulated flat base of Buntsandstein in the Mesozoic.
