Build a handheld distance gun

Measure distance with ultrasound, show it on a small screen, beep when something gets close, then calibrate it and build it into a handheld case.

Time2–3 weekends

Parts₹800–970

Free. Make an account and you come straight back to start it.

Before you start

Tools: Laptop with the Arduino IDE, Tape measure, USB power bank, Soldering iron, only if your screen's pins come loose, Free CAD software (FreeCAD or Onshape), A 3D printer, or card for the case
Skills: A first Arduino project. Some screens and sensors come with loose header pins that need 4 quick solder joints (or buy them pre-soldered). Steps 1–4 use code (or Get the code); step 5 is CAD.
Safety: Low voltage: 5 V from USB. The optional laser dot can hurt eyes, so never point it at anyone.
Prices: Checked 2026-10, with a clone Uno; the top figure includes the optional laser; an original Uno adds about ₹1,950

Step 1 of 6

Distance on the Serial Monitor

Your Arduino measures distance with the ultrasonic sensor and prints it in cm.

Task 01 of 08

Unplug USB. Keep the sensor out of the breadboard: the breadboard only gives every module a shared 5V rail and GND rail.

Check: The sensor's four pins are free for female-to-male jumpers.

Safety: Unplug USB before you change any wire.

You need

9600 baud

Expect to see

Get the codeThe full sketch comes with the build.