Prepare the Track
Off-the-shelf metal stock, including angle iron and carriage bolts, was used for this project. With a 3' door opening, a 6' piece of track is required for full operation of the door. If wheel grooves are small enough, they can ride directly on the angle iron. Since wheels shown had approximately a 1" diameter scallop to the riding surface, the track required a rounded top. One-inch metal building tension rod, purchased at a local metal salvage yard, was cut to length and the ends bent with a torch to prevent the wheels from rolling off the track. A simple Z-shaped bracket placed on the wall as a stop would also work. Next, the rod was tacked with a 1" weld every 1' on the back. A salvage yard may tackle this job for you.
The two pieces of angle iron will be oriented so they form a "U" channel. Total track depth will be less than 2" so the door fits tight against the wall. To create channel, offset the two pieces of track for the correct depth and clamp each end with vice grips. With a spring-loaded punch, center punch four holes at 6", 2', 4' and 5' 6". Drill through center punch with a stepped drill bit to 1/2" diameter. By using a 1/2" hole and 5/16" carriage bolts, adjustment may be made later to ensure a good fit.
Take the angle iron without the welded rod to the door opening to mark the mounting holes. This piece will be mounted to the wall and must be drilled to anchor it into solid wood. Locate studs past the opening. Using a tape and pencil, mark the approximate location of the door track on the wall. Using a stud finder, locate all the studs within the track span past the door opening. Measure the distance from the end of the track to the stud locations and mark this on the angle iron. Place three equally spaced bolts in the door header. Place one bolt into each stud. Drill the marked holes in the angle iron to 1/2". Do not drill holes into the wall at this time.