You've asked a great question! An electron is not "made up" of anything; it is indivisible and cannot be broken down into other particles. Particles that are indivisible that cannot be broken up into other things are said to be "elementary particles." They are the building blocks of matter.For instance, a proton is made up of two "up" quarks and one "down"quark, these quarks, like an electron are also elementary particles and are not "made up" of smaller particles. There are 12 such elementary particles, which include electrons. These 12 are talked about on this website:

It has an awesome video which talks more about these building blocks of nature. I encourage you to look on this website and find more about other fundamental particles!

As far as we can tell, electrons are not made from anything else. They are a fundamental particle.Then again, people used to think that atoms were fundamental particles, too, until we discovered they were made from smaller particles (protons, neutrons, and electrons). But we don't have any evidence to suggest electrons are made from anything smaller.

So far as is known, electrons are elementary particles. They are not composed of smaller parts.