Aarh! Yes I remember it ?..Well?
I tried to search & can?t find it?
It was good idea using the toy cars, just a thought, I feel with the modern Matchbox cars & the way the axels bend with the least amount of downward pressure, this could be a problem.
I can?t remember it was a PVC pipe with a slot cut, which could be drama, depending on length & flexing or an extruded channel?
But it still sounds like a great idea, unless there is a prang & vehicle pile up in the pipe.

With the Tab system it is a good idea to get the main train adjustable pull carriage which the sash cord attaches on to. Also check out the custom made pulley to suit the track, along with the support fixings.
This Hall stage system diagram may help you ;-
http://www.hallstage.com/t70_track_ass_sash.pdf
Also when you hang the track attach ties or cord as a daisy chain between the tab drop holders, this will reduce the strain on the fabric header of the curtain or cloth, when pulling on or off stage. You could just use one cord incremental knotted to either give the fabric hanging folds or at a full stretch.

Can a seamstress become a rigger?  Of course!  Just remember to use heavier thread.

Yeah...I like the toy car idea too..although, as I repeat, it is not mine.  I read it here and the person who described it said they used it for years with no problems.  I was going to ask them how they drilled through the cars.  Did they add bolts or just wire? Of course I was having trouble finding cars that were cheaper than the proper carriers ( which are about 2.00 ea.)  If some one had an old box of them it would be a worthy project. 

Hello all. I just saw you talking about the pvc and matchbox car bit again. I was the one who suggested it originally. I haven't checked in with the Greenroom in a bit since it got hacked. Anyway, to answer your questions. In case anyone else is interested. :)
You were right on the money. I used 2" pvc pipe and cut a slot about 1/2" wide down the length of it with a cap on each end. Just remember to cut that same slot in any couplers connecting the pipes as well. I put screw eyes about every 4 or 5 feet with just enough inside to hold the nut and a nut on the outside to lock the eye in place.
On the cars, to drill the hole I just set them on a piece of wood that fit inbetween the wheels and drilled straight down through from the top then put a screw eye in it with a pair of nuts jammed against each other on the top. I find the axles don't bend that much and we have yet to lose a wheel. They handle the weight quite well and roll nicely. You just have to make sure the slot is wide enough and relatively smooth, especially at the joints where the pipes connect together. If you have the time I'd actually suggest filing down the ridge inside the coupler that connects the pipes so the ends butt right up against each other. A file would work or maybe a dremel tool with the right bit.
$2.00 does seem rather expensive for a matchbox car. I think I paid something like 92 cents at WalMart for the ones we have.
On the pipe flexing, we did have a bit of a problem with that when hanging it, but once hung it's really quite stable with it hung from a screw eye every 5 feet or so. I did end up reenforceing the joints where the pipes connect with pieces of angle iron because the screws I used to hold it together kept popping out when we hung them or took them down.
We've been using these for about 4 years now and haven't had any problems with them, after I smoothed out the slots and widened the tight spots.
I'm glad you found some tracks that'll work for you. I didn't think they'd be that inexpensive, relatively speaking. I might have to pass that name on. The owners of our theater are looking at making some upgrades to the curtain/drop system.