High frequency welding is used for joining PVC foils.
Two or more foils are placed on the welders table
and an electrode is fitted in the machine. Adjustments
are made to apply pressure evenly over the electrode
and finally a current is fed through the pressurized electrode.
I used this method in a number of sculpture projects and
became quite comfortable with it. While working with
the HF welder I made a bunch of specialized electrodes
some of which can be seen below.