This is the hardest part and does require some accurate measuring and drilling, it is simple but don't rush it.
It's time to cut the cutting board. I made my cart 3" x 4" but you may want to alter this to fit your needs.
First mark the center of the cart and the proper sized hole for what you are going to mount on it, I drilled a 1/4" hole. You will need to use a taper head screw to affix your camera or head and you must countersink the screw so that it doesn't touch the rail, if it does touch the rail you will have a bad time.Next we mark and drill the holes for the gliders.
Measure the distance between the slots of the track and mark that on the bottom of the cart, use the center hole you drilled as your center line location. This is the part that needs to be pretty much perfect, If one of the gliders is out of line it will drag too much and make the dolly hard to use, measure three times. After you are absolutely sure your holes are marked where they need to be go ahead and drill them. I chose 3m 8mm cap screws because they are small enough to fit in the holes we will drill in the gliders and I had a bunch of them. I drilled the appropriate sized holes for the screws then used a second drill bit to make the tops of the holes big enough for the caps to recess and sit flush, if you do this be careful not to drill too deep or you will ruin your hole.
Time to alter the gliders. You will need to cut off the little loops, try to cut them as flush as possible that way there will be less sanding to do. You will need to sand these so that they are flat on top, just wrap a piece of sandpaper around a scrap of wood and rub the glider on it, it doesn't take much so be careful so that you don't over sand it. Now drill a hole through them the appropriate size for the tap that you will use to affix them to the cart, tap these by hand and then screw them on. Don't tighten them up just yet, leave them a little loose. now see if it will fit onto the rail. If it goes on GREAT! Tighten the gliders down and try again, you may need to fiddle around with them a bit to get them all aligned but it should be quick.
3D printed quick release
One more step to go.