I did not know PLCC-6 packages also came in a 3mm version. Now I do.

Luckily I happen to have a bunch of clear 5050 RGB LEDs laying around. They will have to do for initial testing while I wait for more diffused ones to arrive. 

Clear LEDs are not really suitable for POV displays as the colors don't blend and you can see the individual component colors, especially when moving. There are ways of diffusing clear LEDs, nail polish, sand paper, hot glue, etc.

The PCBs are 1mm thick, normally I would use PCB scraps to hold it in place while stenciling but I don't have any 1mm scraps. Business cards stacked two deep worked great as a substitute though, and I finally found a use for all those cards.

Stenciled

Stuffed and soldered, one side anyway.

The black-top LEDs made a discomforting popping sound when I re-flowed them. They may have been moisture contaminated, they were shipped in a regular paper envelope from China after all. They all still worked afterwards though.