put "a,b,c" into list1
put 10,20,30 into list2
split list1 using comma
split list2 using comma
repeat with i=1 to the number of elements of list1
    put list2[i] into list3[list1[i]]
end repeat
combine list3 using comma and colon
put list3

-- ouput
-- a:10,b:20,c:30