This is a descendant of the model tool originally created by pouet and iamnotaspy, since upgraded by znix and further upgraded by myself. It converts between Diesel's native .model format and OBJ, DAE, and GLTF, with varying levels of sophistication (GLTF is the most well-developed. Znix's version does FBX instead of GLTF.). There's also an inspector that allows viewing some details of .model files.
Use this instead of iamnotaspy's version of the tool, your sanity will thank you.