Deutex

DeuTex is a wad composer for Doom, Heretic, Hexen and Strife. It can be used to
extract the lumps of a wad and save them as individual files. Conversely, it can
also build a wad from separate files. When extracting a lump to a file, it does
not just copy the raw data, it converts it to an appropriate format (such as PPM
for graphics, Sun audio for samples, etc.). Conversely, when it reads files for
inclusion in pwads, it does the necessary conversions (for example, from PPM to
Doom picture format). In addition, DeuTex has functions such as merging wads,
etc. If you're doing any wad hacking beyond level editing, DeuTex is a must.