I built a small portable slider today.
Material costs are around 15-30$ depending on what you already got.
Aluminium squarepipe 20x20mm, lenght depends on your slider
Two plastic rectangular connecting pieces, as stands
Then i used a saw to cut off 20cm of the pipe and drilled four 8mm holes.
I used M8 bolts etc and two skateboard bearigs per axle.
Be careful to use shims that only touch the inner ring, so you dont block any bearing.
I also bought plastic end caps for the sledge but unfortunately they didn’t fit.
The gopro mount is their standard 3M flatmount version, but any light ballhead could be mounted i guess.
It feels very fluid and rolls perfectly smooth.
As its still about gopro timelapse, i will add a motor in the next few days.