Complex sentence: The ductwork construction starts with the tracing of the duct outline onto the aluminium preinsulated panel, then the parts are typically cut at 45 degree, bent if required to obtain the different fittings (i.e. elbows, tapers) and finally assembled with glue.
Split into simpler sentences: The ductwork construction starts with the tracing of the duct outline onto the aluminium preinsulated panel. The parts are then typically cut at 45 °, bent if required to obtain the different fittings (i.e. elbows, tapers) and finally assembled with glue.