Here are the tools used for the new root by Bumble-Bee & me!
The tools can unpack and repack blobs. Since the blob header is still not fully understood, repacking requires the original header from an existing blob file!
It is able to pack any number of partitions in a single blob (given it fits in the staging partition of course..around 500MB is the limit). The tool should be selfexplanatory from the output it gives if run without parameters, but I'll be happy to elaborate if needed.