Here are pots I purchased during Paris vacation a few years back and just got around to planting up the black shallow one (the far one on the right) recently. It is approx. 3" X 8" and barely 2" tall.
The planting consists of Sedum dashphyllum, Sempervivum 'Red Cobweb' and Sempervivum globiferum subsp. hirtum. I used dental tools to help situate the plants into the narrow container opening and spray bottle to water the plants.