I won't win any prizes for this sump setup, but it's functional. Maybe one day I'll go with a custom box, but I went the low-cost route and used a standard glass tank.
You can't see it in the photo but the sump tank is resting on a piece of styrofoam board. If you're new to aquariums, you should know that if you put a tank on a foam board it reduces the stress on the tank seams by any slight unevenness on the surface it's resting.
Below is my overflow return running to a filter bag resting in a large piece of PVC from Home Depot that I cut holes into the side for water flow. The frisbee on top is to reduce spray and noise from the water coming from the overflow tube.
This photo shows my protein skimmer. I put a small bulkhead through the side of the collection cup to drip into a larger overflow container. In the larger overflow container, I have float switches hanging to read the amount of junk skimmed, and display it on the LCD with a warning if it hits a high mark. This gives me more time to take care of organic compound removed from the skimmer, particularly if I adjust it to skim very aggressively and be alerted to a completely full situation.
The mighty Eheim hermetically sealed return pump has never caused me a problem in over a decade. I highly recommend these pumps, though they are expensive. In the long run, you'll probably save money by not having to replace impellers.
If you're wondering what the T fitting is for, I once had a chiller that I fed by that line. I don't use that anymore, and it's, of course, inefficient, but was needed in the tight space I had in my cabinet at the time.
Finally, I have a little basket on the side of the sump with some chaeto algae as my refugium. It is difficult to see in the photo by I have a light mounted on the side of the sump to grow these macroalgae.
