Color Picker

Color Picker.applescript

on convertRGBColorToHexValue(theRGBValues)
	set theHexList to {"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "A", "B", "C", "D", "E", "F"}
	set theHexValue to ""
	repeat with a from 1 to count of theRGBValues
		set theCurrentRGBValue to (item a of theRGBValues) div 256
		if theCurrentRGBValue is 256 then set theCurrentRGBValue to 255
		set theFirstItem to item ((theCurrentRGBValue div 16) + 1) of theHexList
		set theSecondItem to item (((theCurrentRGBValue / 16 mod 1) * 16) + 1) of theHexList
		set theHexValue to (theHexValue & theFirstItem & theSecondItem) as string
	end repeat
	return ("#" & theHexValue) as string
end convertRGBColorToHexValue

set theRGBValues to (choose color)
set the clipboard to convertRGBColorToHexValue(theRGBValues)

This opens the native macOS color picker and copies the hex string to the clipboard.

1. Open this file in Script Editor
2. Choose File > Export…
3. Make sure to choose File Format: Application
4. Save to your ~/Applications folder

There's more potential here, such as setting up a global keyboard shortcut or letting the user choose which format to copy. Contributions/comments welcome!