this portal frame is easy for use and can load any big size and special size mould for bathtub,after ABS or acrylic sheet heating and soften ,then move the sheet on the mould for vacumm pump and air compressor,then forming the tub shap.Material Acrylic or ABS Optional Accessory Air compressor5HP Vacuum pump: 7.5HP Mold controller: 10KW Short Wave Emitter .