Hi Jeremey,
Thanks for posting a response on this. First I don't know what level of effort is required to do this work as I don't have any C# programming skills. More skilled users like you could educate me on the process of how to go about it if I want to take on this task by myself. Alternately If any users are willing to do this work for a fee, let me know what the fee would be and I will see if I could afford your services.
Second, I only provided the files which Clive had on his webpage (inglegreen.com) sometime back. Unfortunately Clive's webpage has no activity for the past few years and he has left no contact information. If I could contact Clive with regard to this I would have done so. I pray that he is safe and doing well.
I don't possess the legal rights for his code. All I know is Clive never charged for these and allowed free access to this on his website. If I figure how to make this work or pay anyone to do this work, I will keep it open source and attribute all credit/ rights to Clive.
Now let me explain why the need for this little script. This is the only script I have found which can seamlessly export OBJ files from Revit and during that process allows the option to also collapses the meshes down by individual materials. It is very fast and can handle large revit files easily. I have tried alternate paid OBJ exporters, none of them are able to do this currently. Clive's script worked on Revit 2018 but does not work on 2020.
One alternate way of getting an OBJ out of Revit is to export an FBX to 3ds max and try getting an OBJ from 3ds max. I have tried that also. However the OBJ files coming from max collapse all the materials into a single material. So we lose all material information.
As you know Autodesk Revit is a software which dominates the AEC industy. Such a dominant platform has no way to export the geometry data to an open platform like OBJ, either by itself or via 3ds max. This may be either due to oversight or by design, I don't know. Either way its a flaw which needs to be remedied in my opinion.
Best,
Azims