Muros para centrar ventanas.

thingiverse

Here is the text rewritten in American English: "Classic window frames for inverted wall widths. The small piece transforms a one-inch wide window into a two-inch wide one, allowing centering on an even-width wall. The large piece does the same with a two-inch wide window on odd-width walls. This can also be achieved by combining regular pieces, but it uses many pieces, especially in the second case. For modest arsenals, the 3D solution is better. Obviously, they can be used without the window frame, placing them as is. (One side has drawn block separations)"