LS Cheapie Coastal Skybox BOXED v.3 copy mod

20x20x20
Modifiable
35 prims
If it's too dark for you, right click on it, edit it, go to texture tab and check the box "Full Bright".
Door opens and close.
Very simple. About 7 or 8 prims are cushions, curtains, and a pile of books, so if you remove them, you'll get a lower prim skybox.