The DiiiCooler mod: better cooling, better prints
The single biggest quality jump yet. Episode five swaps the weak stock fan for a blower and a 360-degree cooling shroud, and the difference on overhangs and bridges is night and day.
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Editor's note (July 2026): A mod from my 2017 journey on the now-discontinued Maker Select V2. The principle still holds: good part cooling is one of the biggest levers on print quality, and modern printers ship with far better cooling ducts as standard. The DiiiCooler shroud is still a free download (below). If you are starting today, see the current-printer link at the end.
The short version
The stock cooling fan blows air at the nozzle from one side, so a lot of it misses and overhangs droop. The DiiiCooler swaps in a 50mm blower fan and a printed shroud that wraps cooling around the nozzle from all sides. Print the shroud in a heat-resistant material, add the fan and a few screws, and your overhangs and bridges get dramatically cleaner. It was the biggest quality jump of the whole series.
Cool the plastic from every side.Why part cooling matters
After the camera-mount detour in episode 4.5, back to upgrades. A few viewers suggested this one, and a defect on an earlier Benchy sealed it. At the top of the front window and the ceiling of the wheelhouse, the filament had drooped: while bridging those gaps, the plastic was not cooling fast enough to hold its shape, sagging a little on each pass. That is a cooling problem, plain and simple. PLA needs to be cooled the moment it leaves the nozzle, and the stock setup was not keeping up.
Stock fan versus the DiiiCooler
The stock cooler is a 40mm open-intake fan that pushes air at the nozzle from a single direction, so a lot of that airflow simply misses the point where it is needed. The DiiiCooler replaces it with a larger 50mm blower-style fan feeding a purpose-designed shroud that focuses air directly onto the nozzle from 360 degrees. Cooling the fresh plastic evenly from every side, rather than one, is exactly what stops those droops.
The mod kit and printing the shroud
The mod is two halves: hardware you buy and a shroud you print. The hardware is short and cheap, and pre-assembled kits were sold by 3D-printing stores, but it is easy to source yourself:
- One 50 x 15mm brushless blower fan (the heart of the mod).
- One M4 x 20mm screw and one M4 locknut.
- Two M3 x 12mm screws and two M3 locknuts.
The shroud itself is a free download. Print it in a heat-resistant material like ABS (or PETG), not PLA, because sitting right next to the hot nozzle, a PLA shroud can warp or even melt during normal printing.
DiiiCooler fan shroud on Thingiverse
Free STL for the DiiiCooler shroud. Print it in ABS or PETG and pair it with a 50mm blower fan, as shown here.
Download
Installing the shroud
With the printer powered down and unplugged, the swap goes like this:
- Disconnect the stock fan's power and unwrap its wire, then remove the top screws holding the stock shroud.
- Fit the M4 locknut into its mount on the new shroud, then attach the blower fan now, while there is still room to work.
- Mount the shroud. The small locknuts are fiddly; I held the bolts upside down with an Allen key and tightened the nut from the top.
- Seat the fan into the shroud's friction grooves, connect power (red to red, black to black), and route the wire well clear of the fan.
- Test the fan through the printer's control menu before you print.
One real tradeoff: the shroud is bulky and hides all but a sliver of the nozzle, which makes bed leveling and nozzle cleaning harder without taking it back off. Worth knowing before you commit.
The results: best Benchy yet
With the new cooling running, I printed another Benchy, and it was the best quality one yet. Two spots tell the story: the small hole at the rear came out nicely defined and sharp instead of distorted, and the top of the front window, the exact place that drooped before, was almost perfectly smooth with no stringing or sagging at all. Whether you choose the DiiiCooler specifically or another aftermarket cooler, upgrading from the stock fan is a clear win.
Frequently Asked Questions
What is the DiiiCooler mod?
It is a cooling upgrade that replaces a 3D printer's weak stock fan with a 50mm blower fan and a printed shroud that directs air onto the nozzle from 360 degrees. Better, more even part cooling means cleaner overhangs and bridges.
Why does part cooling matter in 3D printing?
PLA needs to cool the instant it is extruded to hold its shape. On overhangs and bridges, plastic that stays soft too long droops and sags. Strong, even cooling from all sides is what keeps those features sharp.
What material should you print a fan shroud in?
A heat-resistant material like ABS or PETG, not PLA. The shroud sits right next to the hot nozzle, and a PLA part can warp or even melt there during normal printing.
What do you need to build the DiiiCooler mod?
A 50 x 15mm blower fan, an M4 x 20mm screw and M4 locknut, two M3 x 12mm screws and two M3 locknuts, plus the shroud printed in ABS or PETG. The shroud STL is a free download.
Does the DiiiCooler shroud have any downsides?
One: it is bulky and blocks most of your view of the nozzle, which makes bed leveling and nozzle cleaning harder unless you remove it. The cooling improvement is worth it for most people, but it is a real tradeoff.
The best single upgrade so far
Of all the tweaks in this series, better cooling made the clearest difference to actual print quality. Overhangs, bridges, and fine holes all sharpened up, and the fix was cheap. If your printer struggles with drooping overhangs, look at your cooling before almost anything else.
The journey is not all smooth sailing, though. Episode 6 is the one where something goes horribly wrong.
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