3D printers generate heat, sometimes a lot of heat. Heat can cause fires, especially if there are flammable items around it. It is always best to keep an eye out on the print. We do not recommend leaving it unattended but if one print is going to be over 24 hours, then it is recommended to sleep in shifts and keep an eye on it periodically.
I’ve been thinking about building an enclosure for my printer specifically to be able to contain any possible fires (with the benefit of helping with materials like ABS). I haven’t found tons of resources for that yet, but it sounds like fire rated drywall and/or cement board might be a good place to start. One warning I’ve seen is that running metal screws through the sheet material can transfer heat to other flammable material.
If anyone has any resources on DIY fireproof enclosure solutions, I would love to hear about them.
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My printer prints for days at a time, as an example the current project is/will be printing for roughly 200 hours, with no problems. To make you feel a little safer put a smoke detector under or near the printer.
I like to set up an old phone with an ip camera app running so I can check the printer from the bed or anywhere I am.
Touchy subject but with prints ranging from a few minutes to well over 72 hours you kind of don’t have a choice. Stopping a print is not always a great idea.
My 2 cents.
Build a fireproof cabinet, keep a fire extinguisher close by and install a smoke detector. You can even have a cabinet with an automatic extinguishing system.
But in the 4 years I have been printing I have only heard of one issue and I think it was due to user error.
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A cheap method to monitor 3d printers for smoke is to use a $20 smoke detector mounted in your printing area and then a Wyze Cam. You setup the Wyze cam to listen for the smoke alarm and send notifications. Additionally you get the ability to easily remote view the printer and do time lapses with the Wyze cam
Fire proof enclosure with a Heat triggered auto extinguishing system. It’s pretty much a ball that explodes when it hits a temp above typical ambient air temps of the enclosure, and explodes, covering your printer and area in the flame retardant.
Need to add a power cutoff to this as an electrical fire can resurge if it’s still has current.
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3D Printing Canada has the Kora enclosures, although a bit expensive for the home hobbyist they do offer automatic fire suppression and smoke detector addons. Jason did an unboxing of one of these enclosures on the YouTube channel
Addons available: Kora – 3D Printing Canada
Wow! Some scary answers that at first i thought were sarcasm. 
Is this more of a worry as you get into the higher temperature filaments?
having said that a smoke alarm is not a bad idea.
I have only printed once overnight. my thing was to make sure i have plenty of PLA and its in a well vented area. I did not have a problem when I did it.
Your slicer will tell you how many grams it will use. You can weigh your spool, subtract the spool weight and you are left with the weight of the filament. You now know if you have enough filament.
longest i ever printed was 53 hours and i monitored temp. But not a bad idea to have smoke detector. i have two of Z wave smoke detectors are sitting around they connect to my Ring Security. So if there is a fire they will ring my phone and wake me up. i bought six of those smoke detectors from Costco USA for 149 bucks connects to your Ring security and that thing works. I burn my food on stove and it did pick up smoke in kitchen and trigger the alarm. i was in my home office and i got a call on cell phone with in seconds of i hear the smoke alarm. so to me Ring did a good job.
I’ve been printing almost 24/7 for 3 months with no problems. There are some older printers that do not detect thermal runaway. You should avoid those. Thermal runaway is a state in which the printers controller can’t detect that the temperature has risen. It applies more power to raise the temperature but still can’t detect it. This goes on in an endless loop. Detecting it is ridiculously easy: If the controller applies heat for 1 minute but the temperature doesn’t rise, just shut it down. For some reason, it took firmware developers a surprising amount of time to think of this. If your printer has thermal runaway protection programmed into the firmware, you will be fine. Otherwise, upgrade it. If it’s an older printer that is not being upgraded by the manufacturer, proceed with caution.
In my case, as a backup, I have a Nest Protect smoke detector mounted on the ceiling near the printer. Nest Protect smoke detectors are networked such that if one of them detects a problem, they all start issuing verbal warnings. If it continues unchecked, they all go off and send an alert to your phone.
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Nice, I’ve got a Raspberry Pi running OctoPrint with a camera
We tend to avoid printing at night. One of the printer we have, its connector for the bed is not rated properly and overheated and melted at one point. We have changed it since for a higher current rated one.
As for some other printers, we have changed the wiring for higher current rated one, and with better insulation…the wires were getting way too hot (it is a good idea to check these while printing). We are using an enclosure, since temperature can drop within the printing room specially at night.
It all depends on the printer you have and how much you push it, but take precautions and never overestimate the quality of the wiring or connectors the printers comes up with…
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It would be a good public service if you would identify the printers that had substandard wiring so that other people with those printers can get a heads-up.
Having said that, I never thought to check the wire temperatures, so, being 25 hours into a 27 hour print, I just checked my wiring and I’m glad to say that my Ender 5Pro, in an over-heated room (I don’t have an enclosure yet) has no overheating issues with either the wires or the connectors.
Thanks for posting that. I wouldn’t have thought to check it had you not pointed it out.