Earlier this year I had an assignment, that needed longer sliding shots. Some 3 meters long.
So I sat down at my laptop and designed myself one.
The first 3 pics show the original design, with a set of tubes, monted on two tripods and a carriage with the camera on top. The rail is 3 meter long and I can load it into my car. I used this assemly for the job.
The 4th till 6th pic shows the alternative carriage, that I made some time later. It enables me to set the shaft of the wheels in an angle, in order to use it on a table, while it moves in a circle.
Dwg files available on request.

Commercial MPP Systems on Vimeo
Relevant shots from 2:19 onward.

That's one versatile rig. I'm building one too.

I adding a Desmond DLB-66 ball leveler and a 701 head to the setup. The rails can then be on a angle, with the camera level, or camera pan and tilt included with the trolly move, or the camera panning and tilting on a circular move. I may increase the track width as compared to your design to offset the taller center of gravity.

Thanks for the inspiration! Your design is simple, clever and highly functional.

After a couple of hours, this is what I came up with. It works well and is strong. To make the rig safer for the camera, I switched the rails to a door track instead of round pipe. The tripods are not sturdy enough for my liking, so I may do something different there. The track shown is portable enough and can be placed any surface, such as between two chairs. So it is simple to setup. I also can use any any materials available , such as pipe or angle iron or square tube, to build longer runs if needed. Once the ball leveler is installed, the track can be used on a slope.

Note to self: remove the pearstone battery pack and use the Sony L battery to reduce weight and height.

I had fun making it.

Thanks Jo, for the inspiration

Need some more inspiration?
Here's a dolly I made last year, a lot more sturdy, I think:
DIY Slider on Vimeo