Simple stackable box without dividers with back support

Stackable containers that don't “lean back” when stacked. Description from the model I remixed from: The original model from @sraj had these both sizes of boxes, but the biggest one was presented only with internal dividers. I needed it without the divider, so I needed to remix it for myself. Boxes are simple, versatile and perfectly stackable. As total wall width is 0.8 mm, with 0.4 nozzle the box will be built with 2 walls, employing a nice mechanical resistance for its size.