What's the best way to use redirects on a massive site consolidation

[MJTrevens]

We are migrating 13 websites into a single new domain and with that we have certain pages that will be terminated or moved to a new folder path so we need custom 301 redirects built for these. However, we have a huge database of pages that will NOT be changing folder paths and it's way too many to write custom 301's for.

One idea was to use domain forwarding or a wild card redirect so that all the pages would be redirected to their same folder path on the new URL. The problem this creates though is that we would then need to build the custom 301s for content that is moving to a new folder path, hence creating 2 redirects on these pages (one for the domain forwarding, and then a second for the custom 301 pointing to a new folder).

Any ideas on a better solution to this?