For a 4' x 8' door to be sliding you need more than a plastic or aluminum track. However you build a door that size it needs to be hung from above on wheels.
A frame made of 5/4 wood with at least one center cross rail could have 1/4 hardboard panels to keep the weight down.
I have used this companies tracks for many years. Look around on the site I am sure they have what you need. Get the track & wheels first then read the instructions carefully before you build doors to fit your cabinet.
Bypassing sliding doors usually have an overlap in the center. Allow for this when you size the doors. Make them 3/8 to 3/4 wider than half of the opening.
Buffer looks decent. The handles in those pictures look like they have had some sort of finish before polishing. Polished raw wood shows every pore and it is easy to pack any buffing compound into the pores (and hard to get it out) Plus any moisture could raise the grain and dull the polished surface. Many types of pore fillers and finishes will work but they need to be completely dry and cured before polishing. I suppose oil/wax could be polished but the surface wouldn't be as durable.
Lots of progress today. I ended up using the table to do the mortises in the legs. I'm still going to get the guide bushing kit because I think I can do some cool stuff with it. Having a proper router table with an easily adjustable fence has changed my life.
Tomorrow I hope to square up the mortises, give it a dry fit and get started on top. The center of the 3 boards above is a little thicker than the others. I think I might route a 1/2" groove in a few places along the edge and use some plywood as a biscuit type of thing to help line everything up.
Thanks! Yeah, I really like it too, I'm going to incorporate a couple thin strips of red oak into the top so it all goes together. Kinda like that awesome candle holder center piece @Cliff just made.