Welcome to the forum!
i have used fishing line to hold down vinyl tracks.
i run it through the tracks and tie it on the inside, leaving two long ends.
(tying it on the inside helps to keep it under control when you are assembling)
it is a bit of a hairy mess when you have ten ends flopping around before you get them tied up,
but then i just tie the ends around the nearest axle and snip the loose ends.
can't say if it's better or worse than other methods,
but it works pretty well.
black nylon thread would work too, i guess.
good luck.