Some Days Ago I discovered Procreate saves the progress of your drawings, so I saved the video of this Time Lapse. 

This is the Time Lapse for the Background for The Offices for the Elevator to Higher Snowdin. For the moment is only used during the morning of the 3rd Day, when Papyrus can decide who visit for a short skit. Just choose visit Sans. Just happened he works there now. 

It's based from that Vintage Photo of the Elevator las Delicias from Valparaíso. In the background itself you can barely see the actual elevator, but the monochrome green palette is also based on the photo.