+1 on the old hard drive magnets.
Very strong, probably wouldnt need over two.
You could fasten the magnets in the cabinet and have square pieces of thin iron on each panel.
There was a young mechanic at work that had the task of making a personnel door out of aluminum angle and plexi glass.
He was trying to figure out a way to hold the door shut . I got a couple of magnets from an old hard drive and showed them to him.
He liked the idea and used them.
He first tried welding them to the frame but the heat killed them, so after finding two more for him, he attached them with screws.
They hold the door very securely. You can open it by applying your weight if your hands are full, but a breeze will not open it.
They are attached to a piece of metal that you can drill holes in and use to attach them to something else, such as wood frame.