can't delete this post :(
Step 1: How Long Will It Take?
Step 2: What Will You Need?
Step 3: How It Is Made!
Then from object type click on box and make a rectangle that is 540 cm x 450 cm. After this right click on the object and convert it to an editable spline. Whit the rectangle still selected go to the modifier tab and select sub-object mode (it is the small plus sign) and choose all 4 splines. Scroll down until you see the Outline button. Type -20 and hit enter (this just adds width to the wall). Then convert it into a Editable Poly by right clicking on the rectangle selecting Convert to and clicking Convert to Editable Poly. Then go to polygon sub-object mode by pressing the 4 on your keyboard after that select all of the polygons and extrude them with a value of 250 cm.
Now go back to primitive objects and make another box with 370 cm x 50 cm x 225 cm
Then move it so that it touches one of the walls. Select the walls, and right click on the rectangle go to Compound objects and then select Pro Boolean. In the settings, click Pick Operand B and click the box object we just created.
Step 4: The Walls and Windows
Now make another box as large as the one we used in the boolean operation to create the window, but make sure this one has a width of around 5 cm – slightly thinner than the wall itself. Now convert it to an Editable Poly as before.. Select the two large polygons (be careful to select the backside one as well), right click and Inset them with a value of 4 cm. Now delete the two selected polys.
Go into border sub-object mode by pressing 3 on your keyboard, select the two open borders, and click the bridge button to connect them with a loop of polys. Make two chamfered boxes and place them as seen in the picture below to create the divisions in the window frame. Finally, make 3 more boxes with a width of about 0.5 cm and place them into the window frame to form the panes of glass.
Select the all of the wall polys. Now go into vertex mode and click on the Splice Plane button. Adjust the slice plane and make the cuts as seen in the picture below. To exit the slice plane mode, click on the Slice Plane button once more. Finally select the indicated polygon and extrude it inwards with a value of around 7 cm.
Info: You have made these cuts to create some guide geometry which will be used to add different materials to the walls, and also to place a lamp behind the bed.
Now fill the rest of the room with any props you have in mind