Parts for mounting a common J-head hotend on a RepRapPro Ormerod printer. The fan duct is an adaptation of an existing design, modified with a different mount as well as angling the fan up a bit to make it lighter and smaller. The "cooling ring" has been cut off since it got in the way of the hotend.
It screws into the regular X carriage in place of the stock nozzle mount. The nozzle will be in the same X/Y spot as the original one, but about 20mm further down, which will limit build height. It has mounts for dc42's sensor board, as well as a modified sensor pad for X homing. Since the nozzle and sensor are about 20mm further down relative to the Z carriage, the pad is dropped down as well.
All parts are licensed under CC BY-SA, except the sensor mount which is GNU GPL (in line with the part it is based on).

Print both mounting parts. Attach optional sensor board to side of fan duct, and if you use that for X homing, print and mount the sensor pad. Use two M3x30 screws through the fan duct, past the groove near the top of the J-head nozzle holder, through the nozzle mount and into the nuts in the nut trap in the X carriage.
The "long" fan duct part has elongated holes so it can be adjusted a bit in height.