I rarely work with SMD LEDs, but I quickly realized that's not easy, to find the polarity, and without putting them under power, you will never know the light color.

So I quickly built me this tester. It's just a CR2032 battery between two parts of wood or plastic. To conduct the electricity I took a self-adhesive copper tape.

Step 1: Quick Cad Draw

I use Qcad to draw the parts needed. I imported them to Inkscape to send the file to the laser cutter.

Nice clean parts, for a quick helping tool

Attached to this step the svg and dxf files

Step 2: The Parts

3mm - 3.5mm MDF or Plexiglas
three screws M3 12mm
three nuts M3
Self-adhesive copper tape
Adhesive tape
One CR2032 battery

Step 3: Mounting All Together

Cut 2 stripes of copper tape. As seen on the picture, make sure, that the tape does not cover the screw holes, otherwise you will get a short circuit.

Now remove the protective paper, and glue the copper on the inside of the two parts.

Use some tape to insulate the middle part of the copper. Do not cover the two extremities.

Take the three screws and pass them through and place the round part. Place the Battery (Check the polarity!)

With the 3 nuts, screw the last part of it and finished. As you can see, it does the job.