This is a small, tight root built around one colour: blue. The ancient sense was kohl, the dark blue-black powder painted around the eyes; from it Hebrew kept the colour itself, the act of colouring something blue, and the tool you paint with. A thin family, but a clear one: the same three letters seen as an adjective, a verb, and an instrument. Every word here is verified against pealim, niqqud included.
The same root runs through the verb system. Each binyan is a voice: it bends the one idea into active, passive, causative or reciprocal. Tap to hear.
Both surviving verbs sit in hif'il, the causative voice: you make something become blue. The plain pa'al "to be blue" is carried by the adjective כָּחֹל instead of a verb, which is common for colour roots.
Same root letters, different noun moulds (mishkalim). The mould tells you the function: who does it, the act of doing it, or the thing produced.
Strip the prefixes, suffixes and vowels. Three consonants remain, and the meaning lives there.