This is nothing ground-shattering as far as CFC's go, but I think it's an improvment on the BYO design. There is a slight increase in cost but I think it's easily offset by the increase in durability and ease of assembly (no JB weld.)
The difference is in how the tees are built, where they used rigid copper tees I swapped them out for threaded tees and hose barbs instead:
25' 5/8" garden hose
25' 3/8"OD copper tubing
2- 1/2" NPT female brass tees
2- 3/8"compression x 1/2"male NPT fittings
4- 5/8"hose barb x 1/2" male NPT fittings
4- 5/8" Hose clamps
25/64" drill (you can use 3/8" but that extra 1/64" makes putting it together much easier)
Knuckle-busters (wrenches for the fittings)
Start by cutting about 8" off both ends of the garden hose. Use your guile and get the copper tubing insde the garden hose, it's easier if you straighten both out first.
Next drill out the centers of the compression fittings so the tubing will slide through them. Drill from the 1/2" threaded side to avoid damaging the ferrule seat.
Once you're done that, put thread tape on all the threads and make it look like the picture (don't forget to put the hose clamps on the hoses before
you put the barbs in the hoses!)
Tighten everything until there are no leaks and you're done.
With this configuration I can run it under full, shut-in hose pressure with nary a leak, BYO's would blow up if you did that. Since I built it, I have added a ball valve to the cooling water inlet to control the wort temp more accurately (my hose water was running at 35F(!) yesterday so running it wide open is out of the question, just a trickle suffices.)
I hope this is helpful, like I said, nothing groundbreaking, but I feel it's more simple than many of the designs I've seen. Let me know if I missed anything.
I was going to build a through-mometer the other day out of one of those liquid crystal sticker thermometers, and then I just thought 'why not stick the thermometer right to the discharge side of the CFC coil?' So I did. I had to trim the thermometer down by cutting off the Celcius scale (antiquated system that it is) and then to ensure it stayed-put, I wrapped it with a layer of clear packing-tape.