If you use old hardware, make sure it is the type that can't come off of the track, like the one posted above. I have similar old rollers that I'm going to use. They roll on the outside of the pipe, but they still can't come off. I have childhood memories of a kid who narrowly missed disaster when he managed to knock a huge barn door off of the tracks, and it came crashing down. Most barn doors have a roller at the bottom which holds the door in line whether opened or closed. My hardware didn't come with one (or the pipe, for that matter), but it's easy enough to rig up something. My barn has modern hardware, and the bottom guide is just a plastic guide wheel. Probably not necessary indoors, unless you have pets or children that might push the door outward. I'm going to try to find a small vintage roller when I install mine. I'm also trying to figure out a clever way to latch the door, as ours will be on the powder room, and some folks like to be able to secure the door when using the 'facilities'.

All the fiberglass that I know of is smooth to the exterior when it comes to the Marvin and Pellas. They do make a fiberglass woodgrain in some of the entry door line ups but I don't know of anyone in a slider that makes that.

I am not sure what yo think a "barn type door" is. Can you describe or post a photo? Barn doors can be on roller tracks, pocket doors, dutch doors, or hinged doors. Or is this purely decorative wall hanging? One guiding principle is that wood works better in compression than tension. This means that if you are using diagonal supports, they should go up from the hinge side and not down. Then the are "compressed" and not "stretched." If you do this, the diagonals are often cut into a notch in the horizontal members Poplar is a good paint-grade wood and light, and relatively inexpensive. Here is a link that might be useful: [63,616 barn door phtos[(https://www.houzz.com/products/barn-doors-prbr1-br~t_696~a_860-14642)

You can look at a company by the name of Panda. They make a Lift-n-Slide system with a track with a single post that sticks up 5/16" of an inch. There is really no other sill or threshold as the rest of it mounts below the floor. Granted you may not want the expense of a L&S system but this would allow you to use your original sliding door panel idea for light and should also help with sound to some extent