the sheet then advances to a cutting mechanism not shown which is adjustable to cut the moving sheet to a desired length fig1 shows a side view of a siding member 22 made in accordance to the heretobefore described process in the preceding description the left hand edge sheet portion corresponds to the upper edge of the siding member and right hand edge portion corresponds to the bottom edge of the siding member if desired a fourth heating forming and cooling station can be installed after the third stage pull rolls to produce the siding member 23 shown in fig2 the modified siding unit 23 shown of fig2 is produced with a corrugation 1e in the center of the siding unit to simulate the appearance effect obtained with a narrow width siding unit fig3 shows two siding units in assembled relationship and secured to a wall by fasteners 1f adapted to anchor the siding to the building structure as can be seen it is readily apparent from an inspection of fig1 and 3 that the outwardly projecting u shaped member 1c formed in the left hand edge of the sheet on the machine table is the upper edge siding member the lower edge of the siding is the right edge of the sheet as described in.