I’ve created a small tool for very specific manipulation of Blorb files. It started out as a more fleshed-out rewrite of bpal, which adds BPal entries to Blorb files. @dfabulich suggested bundling Infocom’s story files with their Blorb files, so I added a mode for that.
And just because it was easy to do, it also has a mode that will losslessly recompress a Blorb’s PNG files with OxiPNG, to reduce the file size.
The motivation behind Snavig was to be able to manipulate existing Blorb files. New authors can create Blorbs however they want, but I needed ways to modify existing Blorbs.
As such, this is a niche program, and probably won’t be of much general interest, but it’s out there! Source code only for the time being, but I can build binaries for various platforms if necessary.