These are the finished pictures from the tiny track dog project. (Man, that was a long time ago.) And the results were: success! They worked like a charm. There was no cable slip, no binding in the track, and the travel noise was minimal. We noticed that the UHMW bowed (approx 1/32″) at the bottom when the cable was tightened down, which was expected from such small bits of hardware. Nick simply pre-tightened the cable, and carefully shaved the dogs on the tablesaw — done.
The track was shaped from composite lumber (Home Despot decking). It ended up cheaper than the equivalent amount of UHMW, slicker (& quieter) than lumber and was less fiddly than strips of maso or arboron. It was also much gentler on our blades & cut mucho quicker than UHMW would have.