The DiiiCooler is a better cooler, but the CiiiCooler is a good alternative.

[RECOMMENDED RADIAL FANS]
Duplicator i3 V1, V2, V2.1 (12V): https://www.banggood.com/3D-Printer-12V-DC-50mm-Blow-Radial-Cooling-Fan-p-980653.html
Duplicator i3 PLUS (24V): https://www.banggood.com/Anet-DC24V-5015-50x50x15mm-2-pin-Exhaust-Blower-Cooling-Fan-p-1530026.html
(Please check the polarity before plugging in the new fan, your own risk...)

The CiiiCooler is a cooler that is to be mounted around the hotend of the Wanhao Duplicator i3.
It provides a 300 degree field of cooling around the hotend for the part being printed.
It sacrifices 60 degree of field compared to the DiiiCooler, but provides a view of the nozzle and a more even flow of air around the nozzle compared to a directional or bi-directional cooler.

Print this item without support; in ABS, PET-G or other filaments that can stand a bit of heat.
(PLA has worked when testing the prototypes, but use it at your own risk.)
Print the CiiiCooler with the flat bottom down against the bed.

[CHOOSING THE RIGHT CIIICOOLER]
CiiiCooler_1-32.STL will work for most printers out there.
CiiiCooler_SHORT_1-32.STL This mounts 2 mm higher up and should only be used if the default one above is too low and hitting the heatbed.

[ATTENTION V2.1 OWNERS]
You will need to print the adapter named CiiiCooler_Adapter_V2-1 to be able to mount this cooler to Wanhao's latest V2.1 bearing holders.

[REQUIRED HARDWARE]
1 pcs M4x20 screw
1 pcs M4 nut (or locknut)
2 pcs M4x12 (For V1.0 and V2.0 Owners)
2 pcs M4x25 (For V2.1 Owners)
1 pcs CiiiCooler_Adapter_V2-1 (For V2.1 Owners, from download scection)
1 pcs 51x51x15 mm radial fan (Look at Delta BFB0512HH for dimensions datasheet)

[MOUNTING INSTRUCTIONS FOR V1.0 and V2.0]
1) Thread the lowest 2 holes of the lowest bearing block with M4 tap.
2) Align the CiiiCooler around the heaterblock and fasten it with the M4 screws.
3) Attach the radial fan to the CiiiCooler with the M4 screws and nut and connect the fan.

[MOUNTING INSTRUCTIONS FOR V2.1]
1) Put the adapter on the lowest bearing block with the holes down.
2) Place the CiiiCooler against the adapter and fasten it with the M4 screws.
3) Attach the radial fan to the CiiiCooler with the M4 screws and nut and connect the fan.

[NOZZLE DISTANCE]
The recommended distance from under the flat surface of cooler to the tip of the nozzle is 1-3mm for optimal performance.

[PID HEAT MANAGER] (use for best hotend performance)
This describes how to make your Duplicator i3 use PID heat management for best temperature control of the hotend, no matter which cooler you use.
(For best results, perform your own PID-tuning.)
Using Repetier-Host, go into [Config] -> [Firmware EEPROM Configuration]
Change the following parameters:
Extr.1 heat manager [0-3] = 1
Extr.1 PID P-gain/dead-time = 7
Extr.1 PID I-gain 0.5
Extr.1 PID D-gain 25

[ADAPTERS FOR OTHER PRINTERS]
Wanhao Di3 PLUS - http://www.thingiverse.com/thing:2011571 (By Castle550)
Wanhao Di3 PLUS - http://www.thingiverse.com/thing:2050157 (By jcheger)

[DONATIONS]
If you find that the item improve your daily life, consider supporting the designer by sending a tip.
Click "TIP DESIGNER" here.