The present invention relates to a method of forming a molded article (e.g., 141) from first and second heated and thermoformable thermoplastic sheets (75, 78), which are each respectively formed in situ from first and second thermoplastic compositions (e.g., by means of extrusion). The heated first and second thermoformable sheets are each drawn by reduced pressure into contour matching contact with the interior mold surfaces (14, 32) of separate first and second mold portions (11, 29), so as to form separate first and second profiled thermoplastic sheets (129, 144) within the separate mold portions. The first and second mold portions (11, 29) are positioned towards each other (e.g., together) so as to bring into contact and fuse together contact portions (159, 163) of the first and second profiled thermoplastic sheets (129, 144). Fusion between the contacted contact portions (159, 163) is achieved by means of (e.g., exclusively by means of) residual heat of sheet formation residing in each of the first and second profiled thermoplastic sheets (129, 144). The present invention also relates to a mold apparatus (e.g., 1) that includes a mold assembly (3, 5) that further includes a first mold portion (11) and a second mold portion (29) that reside between and are rotatably attached to laterally spaced first and second longitudinal supports (171, 174). At least one mold portion is longitudinally repositionable, between the first and second longitudinal supports, relative to the other mold portion.