Ok so I've had a couple more people ask about my skimmer so I'll just put the plans on here. I'm not too good at designing software so I'll just provide pictures, parts list, and comments. All of the PVC parts are from Lowes/Home Depot.
Part List:
-4" PVC (2' section)
-4" PVC Test Cap (The one PVC piece not found at L/HD. Get it from a local plumbing supply store or online)
-4" to 2" reducer adapter (Qty. 2)
-2" PVC (2' section)
-3/4" 90 degree PVC elbow (Qty. 3)
-3/4" (slip) to 1/2" (threaded) 90 degree PVC elbow
-1/2" OD (threaded) x 1/2" OD (tube fitting) fixture
-1/2" OD tubing
-Uniseals (Qty. 2) (I got them from BRS but I'm sure you can find them locally as well)
-Taam Rio 800 Powerhead
-Tetra Whisper AP150 Air Pump
-MicroPore Air DIffuser, Single Model (you can buy online, but I went to my local hydroponics store ((yeah, you know exactly what type of store I'm talking about)) and got it for basically the same price but with no wait time or shipping fees, just call around)
-3/4" Gate Valve (I got my from Grainger's)
-PVC Glue/Plumbers Tape (Tephlon Tape)
General Idea
Inside, Bottom
Inside, Top
Collection Cup (Don't focus on the old chamber. It didn't work well and had to be redone)
Outlet
When making the collection cup, dremel out the lip of one of the 4" to 2" adapters so that the 2" PVC can slide in then glue it. That's how the collect cup is made. Just make sure that the 2" PVC inside of the collection cup is shorter than the lip of the adapter. Also, make sure the 3/4" PVC inlet pipe intruding into the chamber doesn't go in too far. You don't want it to interfere with the bubbles. I personally used tephlon tape instead of PVC glue because I wanted to be able to take it apart if I wanted to tweak it at all. If you're putting yours inside your sump then I would recommend the same. If outside, then PVC glue for the extra peace of mind. Other than that, It's pretty straight-forward. If you use a taller chamber, then you need to get a bigger powerhead. You want 2 minutes of reaction time inside the chamber so gauge your pump accordingly. I only used 17" of the 4" PVC for my chamber due to height restrictions with my stand. I recommend going as tall as you can. For now, I have the air tube just running through the collection cup opening into the chamber to the diffuser. It would be better if it were ran through the side of the chamber at the bottom so it didn't interfere with the bubbles at all, but oh well. It works well enough for me so I have no need to change it.
Anyways, good luck! Please feel free to ask me anything else.