Abstract: Generally large, typically eight feet by two inches by ten or sixteen or twenty-four inches, sidewalls for modular concrete forms are easily, efficiently and economically produced by cutting and by routing sheet-type polymeric material, preferably polyurethane or expanded polystyrene foam. Metal connecting members are produced in standard sizes by cutting and bending sheet steel and/or wire. The sidewalls and connecting members are transported to a building site tightly and compactly in pieces, and then flexibly assembled into precision wall forms at the site with good efficiency at any scale. The wall forms so assembled define a cavity into which reinforcing steel rod, electrical and/or communications conduit, plumbing, etc., may be entered. Concrete is poured into the cavity to create a wall having the form sidewalls as its permanent surfaces.