There are lots of variants hoew to do paper houses and rooms for kids toys.
But this way is the fastest, and a kid can do it even without parents help.
That's why I like it the most, and my son was happy to get a new place for his Lego toys so easy and fast.
Many kids don't liek to do anything too long, they can't keep attention on complicated things, they need to get good result asap;)

We need coloured pencils
scissors
a sheet of paper
At first we need to make a paper square.
The 2nd step is to decorate it like a real room - to draw some pictures on the walls and furninure.
Then we can add a nice 3d-table making just 1 cuts
Now we need to make a real 3d-room doing just one more cut!

And here what we get! Looks really good as for a paper room made for 10 min;)
Vlad and his toys were happy to have a new house;)