They're not fake lockers. It's a row of real lockers that Peter has somehow detached from whatever holds it in place, and is lifting up in the air. In Peter's school, the lockers are inset into the walls in between the classroom doors, as are the ones in this photo:
Note that this is a single piece of metal: the lockers have been welded together and there's a single pane of metal covering the entire row. It's also likely there's a single supporting base across the entire bottom.
When Peter lifts the lockers up, he grabs the bottom lip and lifts straight up. There's about a two foot gap between the lockers and the ceiling, and they slide upward as he lifts. As is typical with super strong heros, Peter also has an impeccable sense of balance, allowing him to lift and hold the lockers one-handed without them tipping forward. (The same power lets, e.g. Superman hold an airplane up by it's nose.)
On the walls to either side of these lockers, there are very clear scratch marks and gashes in the drywall. This indicates that the sides of the locker are scraping against the walls, which you can also hear when he lifts them up. That makes it unlikely that he's installed any kind of device to help smooth the movement -- he's just brute-forcing it.