@walter I know the feeling. I’m really trying to use up my overflowing shelves of hoarded parts. This’ll be useful one day, I swear!
Even though the case is built around the fan, I really like how much room I have in there. It would give me the ability to set up a Bluetooth receiver, or convert to liquid cooling! I was thinking about our conversation in better heat sink design when I was putting the finishing touches on the model. Admittedly, I may just print a better version in the future that’s designed around a radiator 
I’m not sure how well dust exclusion will work with this case the way I had intended. I may have gone overboard on my vents. In theory the fan will be supplying clean air which will help keep the dust out, but we’ll see how it goes in practice.
@aluminumwelder I should have put a zip file in the first post with STEP and STL files. I have put a download link at the below. If you want any other formats I can convert them as well.
SteelMaslow-PLC-Case-V2.zip (1.9 MB)
Just a note, this case is designed to be bolted to a 1 1/2" x 1 1/2" steel tube. You can see it’s location in the exploded view below in my drawings. Because of this, if you try to mount it to a sheet of plywood, the motor ports will be covered. You could solve this by mounting it to the edge of the sheet so the ports are exposed, but I just wanted to make sure you were aware it may not work for the stock setup. I can make a plywood mounted version for anyone who wants to mount it that way.
Or you could do some aluminum welding 
