building a little tesla coil is easy.
The really constraining part of the build is the capacitors.
You need very high voltage, very large capacitors. Even for a small tesla coil.
(and you can't use aluminum electrolytic, they are the big cylinder capacitors you see everywhere, especially in computers, as they are DC only, and the tesla coil needs AC capacitors)

So, you build a tesla coil on top of a cigar box (any old piece of wood) but, then you have next to that a half dozen jars in a tub of salt water for the capacitor.