In my younger days, I used to accompany my late Mum on her visits to Chowrasta Market, along Penang Road. There, along the adjoining side lane, was a stall making and selling popiah skins.
It was intriguing to watch how that Uncle snatched a lump of sticky dough from a tub, jiggled it in his hand, and then dabbed it onto a round hotplate, and rubbed the lump on it in a circular motion, before pulling back his hand. That left a thin layer on the hotplate, which quickly hardened.
His assistant then moved in to peel off that cooked wrapper, leaving the hotplate ready for the next cycle. In the mean time, the Uncle went on to work on another hotplate. Quite efficient.
Haha, if I were to try it, I think I would get the skin of my palm burnt.