So I thought a smaller project would be nice to do.
This very small and simple command block module allows you to place redstone lamps
that turn on when it's dark outside!

Simply throw a redstone lamp on the ground and it will turn into an armor stand.

Any placed armor stand will only show the redstone lamp.
The next time it becomes night, the lamp will turn into glowstone and
when it becomes day again, it turns back into a redstone lamp.

You use a glowstone block to craft the redstone lamp, so this conversion is fair.
Once you break the block, the armor stand will be removed, leaving no traces.

In order to install, you put the .nbt file in a "structures" folder inside your world save.
Then get yourself a structure_block (/give @p structure_block), press the button in the bottom left
to switch it over to the load mode. Enter the name "nightlight" and hit LOAD twice.

There you go, have fun!