Hi, I can't really decide which thing to build from the specified, so I just let you decide. The construction projects would then also be built with many redstone circuits, which is actually my strength. Maybe. I also upload the projects to the Internet.
PS: If you find all of it stupid you can also write your own ideas to me.
Hydroelectric power station.
Biogas plant.
Tree house.
Walls and ceilings max. 3 blocks thick. You can fiddle around for a long time 👍
Space station and submarine are not working well. At least if you are into current models, then they are all very small. Small / narrow doesn't work well in Minecraft.
Every Minecraft player has probably built an underwater station before, ship can be interesting, depending on the ship.
Or how about gigantic spaceships? Like in Star Wars, that you can still build many small ones in such a hall. You can also do a lot with Red Stone there.
I like everything that has to do with underwater construction. But it's your business
