I went to Ace and found these zip ties:
For some reason, they alone were thicker and more rigid than the rest of the zip ties. Tool City Vertical Identification 7.6” Cable Ties, natural pure nylon, rated for fifty pounds, and bundle diameters up to 1.7”. I would provide the part number, but nobody cares. Thirteen dollars for one hundred.
I used a larger bit to make the holes bigger, but they are still too small, and the only larger bit is too large. It should still work, I just do not want to drill a larger hole than necessary. Also, my estimate of four inches from center was obviously off, apparently by a factor of 50%, or approximately many centimeters. Putting the zip ties 30cm apart, with the holes only half that distance apart did not work very well, so I left them loose and pulled them through the caps. I think that it looks better, but not as good as if the holes were the proper size, so the caps sat flush, and still not as good as with black plasti-dip.
Without feedback regarding OBD-II dongle, telemetry software, and cell phone mount, I will go ahead with what I have chosen, and hopefully that is work.
I am tired of spending money! Can I start saving now?