There’s multiple ways to go about Phos’ shell legs that I’ve seen.
Painting is still an option, though you would need to go about it by keeping the fabric stretched while it is painted. One way to do this is to cover your legs in plastic wrap, wear the tights, and then paint over them (the plastic wrap will prevent the paint from touching your skin directly, which can be unsafe for long periods, and WILL stain your stain with Phos stripes for a few days…see: the time I forgot to wrap my legs and had Ultimecia’s leg tattoos for a few days). Another way is to make a duct tape for of your legs and do the same thing. Either way will ensure that the fabric of the tights will remain stretched enough while painted that the paint will not need to stretch much when worn. The drawback of this method is that it takes a lot of time and a lot of paint.
Another method would be to make the tights yourself. I would recommend buying a pair of base tights and adding the stripes with stretch applique. If you use a shiny fabric, this can create an interesting effect, and it will conform to your legs.
You can also piece together two different materials to build the tights from scratch, though if you don’t have much patterning experience, getting the diagonal stripes will be difficult, and you will need to contend with adding a vertical seam somewhere on the tights, as you likely do not have an industrial circular knitting machine (if you did, you wouldn’t be asking :P). The easiest way to pattern this is against with duct tape – make a form of your leg, draw the spirals, and then cut the tape apart and lay it out flat to create the pattern, making sure that you label the pieces well before cutting them apart so you know what goes where. You can always cut yourself (carefully!) out of the tape form where your vertical seam would need to go, and use that as the pattern for the seam.
If you have some digital art skills, you may be able to make a file of the pattern and get tights custom-printed with the pattern, as well.
You may also be able to find a pair for sale, though it will take a bit of googling (I didn’t have too much luck on a quick search, but I didn’t look terribly far).
I hope that helps! Good luck :]