Single Slit Thought Experiment

Think of what even the same size would mean. To make a hole or even a slit, you need the material at that position to be "cut" out. An electron is a subatomic particle and has enough "space" to move through the "solid" metal too. So with this intuition, you can say that well, you really can't make anything the size of an electron rather than the electron itself. An electron can literally travel through solids - with no holes. In short, a slit of that dimension will not be practical to make or even exist and even if there were a single slit, what would it interfere with? A single beam can't interfere with itself, and as a general rule, you need atleast two waveforms to have an interference pattern.