Here’s a little (literally) project I made a while back. It’s all balsa, colored with markers and detailed with a 0.005mm inking pen.
As you can see, before placing the roof & door I placed several pieces of wood inside to make a workspace & various non-descript (but useful-looking) items. It’s hard to catch with a camera all the details that are inside there, but it’s clear someone has been working. It’s very lived-in.