Yes, I knew about the existence of tc-ext-tools, but it was not what I was looking for.
Currently, the extensions I maintain are abduco, dvtm and zpaq. Making extensions for them is extremely simple, because you only need to download and run make to build the programs. However, I wanted to do this in an automatic way to facilitate updating them.
I searched for available tools, but I found them (and, in particular, tce-ext-tools) too complicated for my purpose. Only reading and understanding the documentation and the examples would have taken me much more time than writing the few lines of shell I needed. Moreover, since the extensions were so simple, I did not want to maintain more than a file for each of them, so I wrote tce-install.
The script currently has less than 150 lines, which is orders of magnitude smaller than tce-ext-tools. As you can see, the examples included are very simple, and it is not intended to do much more. It was supposed to be a tool for personal use, but I thought somebody may find it useful.