Making stuff like this still requires specialized software, but software development is far more readily available and accessible. The proliferation of software is also essentially effortless, so a terrorist group or similar could have a single team supplying standardized designs worldwide.

Consider the hobby of FPV drone racing. The designs and plans are widely available, and you can get a top-notch drone for about $2000 for a first-time purchase (less for the subsequent ones, since you'll already have goggles/radios). These drones are regularly built by teenagers and it's not difficult at all to add capabilities to the drones, such as target tracking, autonomous operation, software-defined radios for jamming resistance, etc.