I don't condone jamming but if you want to tick off a local yahoo that gives you endless crap on air you can build a few milliwatt single channel solar powered transmitter and toss it up a tree near by so it only messes with them and has a range of a few houses or so.
If you replace the crystal or parallel connect it to a piezoelectric speaker they can become wideband RF jammers around the frequency, did that as a kid but not absolutely sure if that's how I wired it. The piezo acts like a crazy unstable quartz crystal making a ton of AM noise.
Can purchase those solar lights for a dollar and series wire a few to drive a single transistor crystal oscillator, and at night they will run on the batteries they came with. Real cheap and effective. Makes you a beacon and for the a-hole a localized jammer.
If you want to make a noise maker out of it you can wire one of those LEDs that change colors slowly when powered and paint the bulb black so no one sees it. The tiny circuit in the LED bulb throws off a bunch of weird groaning PWM sounding stuff when wired in series with other circuits. I'd bet even a self powered beeper or buzzer if mechanically dampened so no one hears it with their ears would create AM if wired the same way into an RF oscillator and take almost no power to run for hours or days. Maybe even a self blinking LED would work this way. Experimenting being all part of the fun
Wouldn't be any harder to build than a bug, but legality is another story and you certainly don't want a bomb squad to come out from a neighbor that finds it thinking it's dangerous. Just make sure it's made of junk because someone will find it and inevitably end up in the trash, or posted on reddit asking people what it is.