If you place something “in the cloud” generally you would mean placing data on a remote server. In the case of this Bluetooth-controlled cloud lamp by David and Ryan of Eclectical Engineering, it’s designed to literally look like a cloud.
The cloud shape is formed with paper lanterns forming the basic structure of the lamp, while polyester fiber fill on the outside to provide the soft fluffy look that you often see in the sky. Inside of this cloud shape, they inserted five NeoPixel programmable LED strips, which allow the cloud to light up in different colors and in different patterns, depending on how it is programmed.
Besides the NeoPixel RGB strip, this project used an Arduino Uno (ATmega328), a Bluetooth module, and quite a few other items included on their writeup. Code for this project is available here.
They are quick to note that there could be some fire risk if things are soldered incorrectly, so be sure to have a fire extinguisher close (a good rule generally). Also, they used JST connectors to plug in the strips. This allowed for easy connection, but they also note that one should make sure to keep the male and female ends consistent, otherwise you may “straight up murder your LED driver chips.” Foolproofing a design is certainly a good practice for any project, whether it’s mechanical, electronic, or even cloud-based!