Recently, I want to make an advertisement for aluminum-plastic door at home. 12m long eaves extend 0.8m.. Is aluminum-plastic plate installed on square pipe or angle steel?

No, you have to nail a layer of wood board on the square pipe or angle iron first, and then stick aluminum-plastic board on the wood board. When you go to the building materials market, as long as you say whose house you want to buy, the seller will be happy to tell you, and you can also saw the board for free (to the size you want). If this is the first time to do this, it should be waterproof. If you get wet in the rain, the board will be moldy and the aluminum-plastic board will fall off. That's for others.