Now for the latest update:
To recap, here’s a couple pics of the build so far:


That second pic was taken last Thursday.
Saturday, I discovered that the poplar boards I’d bought for the trap had warped, and were the wrong width. Apparently 1/2 x 3 x 24 actually means 1/2 x 2 1/2 x 24. Having only eyeballed things in the store, this threw off all my measurements, and as a result, the 2" aluminum I bought is now clearly too narrow.
So, I returned the cheaper wood, and bought a bunch of basswood instead. $7 for one 3" wide 1/2" thick board. Ouch.
I also returned the aluminum; and as there was no 2.5" replacement, I went online to see if it was feasable to get some in that width there. Luckilly, I’ve found a supplier which will not only cut the aluminum to the exact size I need, but can also provide it in a 1/16" thickness, which will look better. I’ll be ordering that shortly.
On the plus side, as a result of the change in dimensions, the chrome part I bought to use for the side knob, which I’d thought was too large, has turned out to be just the right size. All I need to do is paint it, and get a knob to stick inside it and it’ll be pretty much perfect. I’m considering painting it red instead of neon orange, btw. I think the orange might be too garish for the movie-style color scheme I’ll be using on the rest of the trap.
Then, last night I went online and looked everywhere trying to locate something I could use for those colored boxes on the right side of the trap. I didn’t have much luck. The best I could find was some colored acrylic sheet I could cut to size… but I was really hoping for something with more style to it. Something like a beveled rectangle, or one with slanted sides, like the 1/2" red neon lamp hats radio shack sells. The problem is, the ideal shape for the ones on the side of the trap are more like 1 1/4"x1/2" for the red one in the center of the aluminum plate, and 5/8"x3/4" for the four set into the side panel. Also, neon lamp hats don’t tend to come in colors like cyan, orange, or yellow.
So, I dunno what I’m gonna do for those. Like I said, I did find some reasonably priced acrylic in the right colors, but I don’t just want to copy what’s seen in the cartoon, I want to make somehting that looks like a real device.
Finally, today, I went to Lowe’s, returned the white plastic sink part I was going to use for the base of the hose connection, and picked up the more expensive one in black instead. I also picked up a brass 1/2" pipe thread to 3/4" hose thread adapter, and a black hose quick connect.
The end result doesn’t look precisely like the connecton seen in the concept drawings, but it is a lot more sturdy than anything I could have made out of wood:

…which is important, because I don’t doubt that eventually someone is going to try to dangle the trap by the hose.
Anyway, that’s the current state of things. I hope you like the direction I’m going in so far!