After much searching & trying other already available print cooling fan setups, I couldn't find one that I was happy with for my C-Bot.
This print cooling fan setup uses 2x 30mm fans, with the height being adjustable via the rear mounting plate.
The whole assembly attaches to the rear of the main carriage and has a very low profile (ie, doesn't get in the way).
All parts are oriented as I printed them - you will need to use support, see print notes for more info.
The small notch on the rear mount plate should face the rear surface of the carriage, this is so you can fit a cable tie through to secure your fan power cables :-)
You'll need a few M3 bolts of differing lengths (exact details to be added) along with suitable M3 nuts.
You may feel that when you have printed this, some of the parts feel a bit light & not that strong...this is one of those occasions where the whole assembly becomes a lot stronger when all the parts are joined together. I would suggest that you assemble all the parts together first (including fans & ducts), before attaching the mount plate to the carriage as it is a lot easier this way round.
I have used this reliably now for a reasonable amount of print time (20+ print hours) without issue and have found the cooling to be excellent. It should still be regarded as work in progress, but I feel it is completely usable.
I used PLA & it works fine. I printed this using auto generated support in Simplify 3D - you will need support for the upper arm & probably the fan duct itself.
I printed at 0.3mm layer height and it came out perfectly OK - 0.2 would make the fan duct smoother to look at, but isn't necessary.
At 0.3mm layer height with a 0.4mm nozzle, I used 3 perimeters & 4 solid top/bottom layers on all parts.