You’ll end up with two circles that look ¾ complete but are lacking the middle part to connect them together. To convert an oval track into a figure eight track plan, first you need to break apart the standard oval track and remove the straight pieces and interchange them with 4 curved segments that will be added onto the exposed end of each section you just seperated from the oval track.
Both N scale and HO scale are excellent sizes to fit under without obstructing the view. They are commonly used underneath Christmas trees as a decoration that helps set the holiday atmosphere. Simple oval continuous running loop too loop track plans are the easiest type of track plan to utilize.