A method for preparing a molded article includes the steps of obtaining a polycarbonate resin and molding the polycarbonate resin. Alternatively, the blank and rails may be enveloped in a thermally active PVC or similar material. The apparatus includes a plurality of vibration sources that impart vibrations to the material. The pipe can include a short top pipe section and a long bottom pipe section of smaller diameter, whose upper portion can be pulled up through the top pipe section when the top pipe section is damaged.