Whenever we go outside, there may be need of voltmeter. We may not carry the traditional voltmeter every time. Some times we may forget or we cannot carry simply due to its size. So I had a thought to make a tiny voltmeter as a key chain. While going outside we will carry atleast 1 key. It may be either a vehicle's or a house key. That's why I made the voltmeter as a key chain. It can measure from 3v - 30v DC.

Step 1: Parts Needed

LED voltmeter
Dupont jumper pin and plastic housing
Any plastic box
single lead wire
super glue

I used tv cable coaxial that comes with plastic housing

Step 2: Making the Probes

Crimp the dupont pins, so they are used as probes.

Step 3: Preparing the Box

Cut the plastic so that LED voltmeter is fitted exactly. Cut a plastic sheet so that it is used as cover.

Step 4: Inserting the Voltmeter

Insert the voltmeter and glue it

Step 5: Making and Fitting the Cap

Take two plastic tubes so that one can be inserted into another (I used ball point pen and gel pen refill's).
Cut a slot and drill as shown in the pictures.
Please follow the pictures for fitting the cap.