A dictionary might be much better suited for what you're trying to achieve.

builds = {'a': "123", 'b': "456", 'c': "789"}
build_src = ['a','b','c']
build_list = {}
for word in build_src:
    build_list[word] = builds.get(word, None)
print build_list

Output: {'a': '123', 'c': '789', 'b': '456'}

Is this what you want:

build_src = ['a','b','c']
build_list = {}

for word in build_src:
    build_list[word] = 'build_'+word.format(word=word)
print(build_list)

output:

{'a': 'build_a', 'b': 'build_b', 'c': 'build_c'}

you can use something like this :

build_a="123"
build_b="456"
build_c="789"

build_src = ['a','b','c']
build_list = {}

for word in build_src:
    globals()['build_new_var%s' % word] = word

it will give you what you want, something like this :

print(build_new_var_a)
print(build_new_var_b)

and the output will be :

a
b

but using dictionary would be a better solution , but if you need this for a particular reason you can do this too .

As suggested in most of the answers a dict is the solution to your problems.

Option 1: through a pair of lists thanks to zip

In this case the tuple is formed by the zip function which returns an iterator which is consumed by the dict. This iterator merges the 2 lists by preserving the item's index.

Note: if you are planing to use 2 lists with different length you might be interested in having a look to zip_longest.

keys = ['a', 'b', 'c']
values = [123, 456, 789]

build_src = zip(keys, values)
build_list = dict(build_src)

Option 2: using dict comprehension

You can use a dict comprehension in case you want to explicitly show the loop during the dict construction process.

keys = ['a', 'b', 'c']
values = [123, 456, 789]

build_src = zip(keys, values)
build_list = {key: val for key, val in build_src}