My monolith blaster was missing the door when I thrifted it, so I tried replacing it. This is the third version I printed, and it finally turned out just how I wanted it to. Hopefully this is helpful to others with the same problem.
My college added the supports for me, and they used tree supports and oriented it so the hinges faced up.
I think this could be used as a starting point for an extended hopper, but I chose not to for now. It would only take a very basic change, though, and if I feel up to it, I'll update this with the new file.
The author marked this model as their own original creation.