Is one allowed to make the payos wet on Shabbos and curl them with a comb or by hand?
If the person always curls his payos (and therefore the payos have a curled shape already), the payos may be made damp and can then be curled. They should not be curled when they are very wet because the person would then be squeezing water out of them (sechita).
Ketzos Hashulchan (146) discusses whether curling payos is considered “building”. He writes that the reason one can be lenient is because the payos already have a curled shape, and the person is only “adding” to the already curled shape. He compares this to adding on to an existing ohel arai. The minhag is to be lenient and to curl payos. The minhag is also to only curl the payos when they are damp and not soaking wet, as then there is no concern that the person will inadvertently squeeze water out of the payos as he curls them .