I worked up this plan a while back as an exercise with the Atlas track geometry. It uses a lot of little fitter pieces to achieve near-perfect track fits with no flex-track. The plan probably needs a few inches added to the length and width of a 4' x 8' table.
Two trains can run simultaneously on the figure-8 circuits if they are synched to not run into each other at the crossings, as shown in this video:
https://ogrforum.com/t...18#57038617432409918
A good way to enhance this plan is to add yard tracks on an adjoining shelf.