The tweezer design supports both regular LEDs and the smaller Adafruit LEDs Sequins. If you're using Diffused LEDs with leads, we'll have to cut the leads short to fit into the slots on the tweezer. Mark one the ground lead so you can tell which them a part then they're trimmed short.
Trim the leads to about 9mm short - these will be fitted into the slots on the tweezer.
Insert the leads at an angle so they fit inside the slots. They should have a snug fit.
Always check to see which side is positive and negative when testing batteries. You can always mark the end of the tweezers or add + and - symbols by editing the CAD files!
The smaller LEDs are easier to attach using a couple of small drops of Bare Conductive Paint.
Make sure not to use a lot, just a small drop or two will make a good connection to the conductive pads on the tweezer.
The LED Sequins are tiny, so use a fine tip tweezer to help position it over the drops of conductive paint. Apply a small amount of pressure to ensure the all of the pads are touching.
Let the paint dry for at least 15 minutes. If the LED gets dim, try applying a small amount of conductive paint to the top of the LED Sequin solder pads.