Thanks Dougal, interesting reading.
I took some pictures of my attempts to use those WS2812 on a breadboard for prototyping, thought I would share.
The first try was to solder them on angled headers, after bending the header's outer pins toward the middle one so they're somewhat aligned with the led pads.
This is when I burned some leds, I was using too much temperature and stayed too long on each pin because of the bad alignment with the header and they large thermal dissipation.
If I was again to try something similar i would probably use some thin wire instead of the headers.
After that I made some simple PCBs by toner transfer and chemical etching. That's already really easier to solder, but using flux is needed (mostly because of the poor quality of my PCBs).
Then I did a new PCB design adding the passive components needed to spare space on the breadboard.
That was the first time I designed a PCB for "industrial" making, I ordered those - the green ones - from seeed studio.
I realised a little too late that I put the pads on one side and the traces on the other side, with nothing linking them

To learn my lesson I used them anyway, recreating the connection with wire and components legs remnants.
Man this solder mask thing makes it so easy to solder the surface mount components ! No flux needed here.
I think this is actually faster to solder than a through hole version would be - not counting the wiring step that you shouldn't need to take if you double-checked your design in gerber viewer before ordering...
Then I made a "final" version and ordered it from the fritzing fab service. It arrived two times faster than from seeed studio but cost me five times the price.
Now I can play with them on a breadboard
