So, continuing in the 'I can...but should I?!' vein I give you:
Primochill 13/10 acrylic threaded (hastily) to G1/4:
Not as easy to thread (requires more force) as 12/10 but the thread is more complete. A little cutting oil improved things. I'm not sure whether this will be helpful as I suspect it wouldn't seal (no shoulder for an o-ring) but in the spirit of spraying water all over the kitchen, I plan to give it a try when I have some spare time. Also, not just before the wife's parents arrive to stay
and EK 16/12 tapped to G1/4:
This was so easy to cut the thread I thought it was just way too big and wasn't going to work. Pic is with a standard G1/4 stop plug in and the tube full of tap water. No pressure to speak of (other than 0.9m head) but I did try blowing as hard as I could into the top and it didn't leak at the bottom. Again, I'll try and get a pump on this for giggles when I have a chance. As long as it doesn't blow the thread out, it might actually work as the o-ring seats on the flat end of the tube. EK cut theirs to a nice flat end. Primochill leave a jagged edge that looks more like they snapped it.
Last update I have is round two of fans. I need (unless I want to buy, mount and wire 9x140mm fans) 200mm fans with a max depth of 25mm or the fan grill won't fit. This rules out the majority of 200mm fans out there as they're 30mm thick. Tried the Bitfenix Spectre Pro and hated it. Noisy, wonky bearing, horrible quality to the sound. Also, when I put the fan grill on, it made the nastiest wailing I've heard from a fan that wasn't cooking its bearings. So next try is the Aerocool Dark Force:
I think I'll stick with them at least for now - yes, I'm that enamoured of them! They're really cheaply made, not perfectly circular (you can see and feel them wobble as they go round) and there's enough flex that if you turn them from vertical to horizontal while they're spinning, the blades hit the case.....but they don't look offensive and they're quiet. They don't push a massive amount of air even at full speed but it's enough for a silent setup I hope! They should last me until Noctua get their 200mm offering to market - which is delayed again. I'm guessing that if I want those when they come out, I may have to work out a nice looking way of spacing the fan grill away from the case by 5 to 10mm though. Can you say "Follow-on project!"?