Transparent Backpack Image Rendering

[CakeandBacon]

Hello, I am currently working on my first hat/cosmetic for the game. It is made of glass and, as such, transparent. I was intending on using Half Life Model Viewer to render a backpack image but it doesn't seem to have a transparent background option. What would be the best way to render an image with the correct TF2 lighting and transparent background for use as a backpack image?

[CakeandBacon]

I followed this tutorial using images from the Half-Life Model Viewer and was able to get a transparent background!

https://wiki.teamfortress.com/wiki/User:Bojjob/GIMP_technique