I just stumbled upon a pretty cool youtuber and a problem many of us have faced in the past – finding the perfect continuity tester.
In most cases I use my bench multimeter but a small dedicated device just for this tast would be awesome.
Here comes Leo’s Bag of Tricks!
First of all, his video:
He’s a pretty chill dude and explains his circuit in detail. Definitly worth a watch!
I wanted such a device for myself and plowed through my parts bin. I dug out a primitive tester. It sends 4.5V through the circuit for testing, lighting a little incandescent light bulb and a beeper.
First of all, this is the device:
The back compartment houses a replacement bulb and a place for the batteries:
You can pop the front and the back of this thing, thats rather nice:
A minute of gutting later…
Unfortunatly the beeper is glued in. I drilled it out but I think you can wiggle and break it if you like.
Eyeballing and meauring the space inside…
~timewarp~
So I just took Leo’s design and placed it inside the TESTFIX 
I’ve left the space for the beeper somewhat flexible so you can fit different beepers in there. The LED in the middle has a 10mm diameter.
The battery holder was changed from 3*1.5V to 2*1.5V. The spare bulb was kicked out
I put a piece of plastic in the place where the switch originally was – mainly to prevent stuff from getting in there.
Done!
The device in action 