I wanted to replace all the hollow doors in my 100 year old house, back to something that resembled the age and workmanship.  When it came to the closets, they were all full doors which tends to take up valuable space and bifolds,…well I think they are unattractive and they also would require hardware installed into the new floors.  A much more attractive option was finding solid, used doors, cut them down the center and install with hinges on either side.  For sure there is some sizing and added trim required but in this old/new house, it was the perfect solution.