Looking for a tablebase data mining tool

[Wulff]

Hi,
I am back working at my own tablebase generator, which is using DTM metric.
I am looking for a tool to help me debug a few problems, and I am hoping that someone here has a tool, or knows of a tool, that can extract all positions from a given tablebase with e.g. mate in 3, and put the positions in .fen format in a text file.
I have Syzygy, Nalimov, Gaviota and Scorpio bases available at the moment, but if a tool exists for another format, I am willing to download anything needed to get me closer to my goal.

Any ideas ?