Two Dictionaries + 3 digits

So what might my options be?
I can merge the dictionaries, but i'll need
Dict 1:
aaa
bbb
ccc

Dict 2:
aaa
bbb
ccc

To wind up running like:
aaaaaa
aaabbb
aaaccc
bbbaaa
bbbbbb
bbbccc
... and so forth.

I understand it will scale quite quickly in size doing so if I just make the dictionary, both files together are less than 1 meg in size so I'm not sure how quickly that'll scale up.

However, I also need to append 3 digits, 000-999 increments to the end of Dict 2 OR to the wordlist with both dictionaries merged.

Is there a way to use two dictionaries with a 3 digit mask appended to it and I'm drastically overthinking it or can I merge the two with appending every word in dict 2 to dict 1. Thanks