Not sure what you mean by ugly? With the cover on you can tell anything was done to the TMIC..
I got the 3/8" channel from lowes. All you need is one piece as its enough to cut into the 4 smaller pieces. I also used low profile nuts and bolts from lowes as well and it worked perfectly. No need to trim anything on the cover. One thing I also did differently is I only trimmed down the side of the channel that sits on top of the plastic end tanks. The other side snugs down nicely on the IC core for a nice smooth appearance.
Here's a pic of what I'm talking about