AMD

AMD is an archive format used for storing model data in the GMO format together with particle effects and other misc files.

Files of this format always have the .amd extension.

Amicitia
Amicitia allows you to see, export and replace all the different data types inside of an AMD. Sadly it does not allow for adding new files into an AMD only replacing.

Noesis
Noesis is a free tool for viewing and converting between hundreds of model, image, and animation formats.

It utilizes a robust plugin system, with support for native extension modules and Python scripts. Noesis is a helpful tool due to its simple GUI.

Noesis allows you to convert the GMO data contained in AMD files into many common model formats. It also includes a batch option.

Warning
For exporting AMD and GMO files with noesis it's recommended to use the fbx_2017 plugin located in the optional plugins folder. (To install it copy it into the normal plugins folder).

Noesis does not support any kind of material animations.

Another thing is that Noesis does not have neck_bender support so any amd containg that file will export with corrupted animations.

GMO2AMD
GMO2AMD is a Python script that allows you to make a new AMD from your GMO model. However it doesn't allow for adding any other kinds of data. It also has a Commandline .exe format if you don't have Python installed. Simply drag and drop the GMO file you want to convert to AMD onto the amd.py or the program's exe to convert it.