Here you'll find the model extraction tools written by
nothingness on the old forums.
You can download the utility, and the source code, here.
Recently I remembered about the game and I found some time to try again recreate the models format. Generally, it's stored in a models.bin file (machines, buildings) and in files with the extension *.psb (map tiles), *.arb (artefacts, trees, plants, etc.) from a pdata directory. I enclosed my program to extracting.
Usage: binex a <filename to extract, part of this name or dir branch> <input filename>. Copy program binary to machines root directory. Run command prompt and change dir again to game root (e.g. cd c:\games\machines). Now type binex a .x models.bin to extract all *.x files from models.bin, similarly for *.arb. For *.psb type e.g. binex a .agt pdata\m_desert.psb.
I can't discover orginal objects coordinates so they need to be pieced together, but I think that isn't a big problem.
I hope that in any way it will be useful for something. Meshes can be imported and smoothed in any 3D software. Don't ask how to export new models to original game. I don't recreated whole format and I am not able to do it.