This isn't my own original idea but hopefully someone besides myself benefits. I actually think I saw Tom Barr post a picture with a similar version of this.
I didn't only build this to make the occasional "I might be too busy for this today" water change easier to stomach by being more hands-free, but also because when I tried to do this with my regular hose-style python, I found that leaving the siphon in the water floating caused a significant decrease in flow due to the kink over the side of the tank. This "large" piping allows much more flow without having to hold a hose straight.
Doing 50% water changes in my planted tank, I don't always gravel vacuum, or if I do, it's usually not 20 gallons worth of time.
I built the contraption pictured here out of 1/2" PVC (with a 3/4" inlet) and 5/8" ID braided tubing which hopefully will not kink like my first attempt at a DIY Python with unbraided tubing.
I figure I'll vacuum with a standard siphon setup into a couple of my standard 2 gallon buckets and then start a siphon with this PVC equipment to my bathtub) to do the rest of the 50% WC.
It is built so that it will break siphon at the height of my filter inlet, so that I can trim plants - or watch TV - until it gurgles and then use the swivel hose attachment at the other end to hook up to my faucet waterbed pump and re-fill the tank.