This model has a couple of options. You can print the walls one at a time (Lying down) or all at once (Standing Up). I printed these all at once. The other option is to use skirting or wheels. All the files are the same expect these. There are locators on the frame for the wheels, so locate the frame towards the back of the trailer. There are also locators on the front of the trailer for the hitch and electric meter. I haven't attached the meters in my photos yet. (just forgot). By flipping the frame over you can make the trailer LH or RH meaning you can have the windows and doors on either side.