It took longer than expected and caused me a bit of frustration but in the end I did complete a dog excrement extractor. And the price of the one in the catalog promptly dropped to $15.99. But I still came in cheaper.
Step 1: A Little History
Plan B was to use epoxy in a warmer environment. I thought the cold was screwing with the ability of the epoxy to set-up. I was wrong because Plan B didn't work either.
Plan C was to use special metal bonding epoxy. It was special in that it didn't bond worth shit.
Plan D is where I ended up. This entailed ditching the aluminum stock and using a plastic frame filled with epoxy similar to how I made my gutter rake. This worked and will be the version detailed here. Because of these ups and downs I didn't do this project as efficiently as I would have liked. Specifically I would have gotten all the parts built and then epoxied everything together. This is how I'm going to present the project and hopefully it will flow well. However, I think there will be some minor discrepancies between the photos and descriptions because of this. If you would like clarification on a point please feel free to ask.
Plan E would be to try using the aluminum stock again with JB Weld. I didn't think of this until I was half-way done with Plan D.