In cell A1 enter:
Now is the time for all good men to come to the aid of their party.

Then color good men red.

Then enter and run this macro:

Sub red_picker()
Dim r1 As Range, r2 As Range
Dim s1 As String, s2 As String

Set r1 = Range("A1")
Set r2 = Range("A2")
s1 = r1.Value
l = Len(s1)

For i = 1 To l
   If r1.Characters(i, 1).Font.ColorIndex = 3 Then
       s2 = s2 & Mid(s1, i, 1)
   End If
Next

r2.Value = s2
End Sub

This is just a sample of the technique, adapt it as you choose.