I think it’s important to ensure that these tubes are water-proof (given how finicky the strips are even if they’re “waterproof”).
I use PEX tubing. Then got the corresponding end cap for the tube. I then drilled a hole through the end-cap that will accept an appropriate cable-gland (to pass the pigtail). This allowed me to apply the right amount of tension to the strips (to keep them secure and flat), and once the cable-glands are tightened, everything is waterproof.
Have not tried bending the tubing yet. Was thinking paint stripper hot air gun and tie down strap to assist, but have not decided on size of arch or anything yet, that is for next year.
The colours are a 'color wheel' (note american spelling for google) that starts on a different pixel for each redraw then delay. Its a simple effect I have coded in my DMX pixel controller.