>>7343842Radar isn't quite that simple... Also, the range would be way too limited to be effective using a household microwave emitter, the signal strength dissipates according to the inverse square of the total distance, and only a fraction of the signal is reflected, the rest will be absorbed. Even if you had enough sensitivity you would have issues with background noise. You could do it with enough power but then you can no longer use the household components...
The homebrew automated sentry turrets you see have no depth perception. They use a single camera and target any movement. If you wanted to make a useful tool you'll need to have some serious machining precision, be very skilled in trigonometry, and be beastly at programming multiple cascading components.
It's a novel idea, but it's not practical for real world application unless you have the resources to do it right.
