Safe, cheap, heated enclosure solution for New England garage Hopefully this isn't against the rules as it may fall under &quot;opinion&quot; more than a concrete answer, but I'll ask anyway.
I live near Boston and it gets cold here.  My Ender 3 Pro is out in a detached garage with no heat and I'm pretty sure the garage getting down to about -12 °C (10 °F) has ruined a few prints for me. Also I'd love to print in ABS at home as well and I think I'd need an enclosure for that.
Now, the printer technically already has an enclosure. It's in a box made out of plywood with some clear acrylic doors on the front, but I think the box itself has too much extra room and doesn't retain heat well enough (thin plywood?).
So my question is, for anyone with experience printing in cold environments, what are some cheap/easy ways to keep the enclosure warm, preferably as safe as possible since I can't always watch the print.  I have a small space heater in the garage but I turned it off last night because I wasn't sure how safe it'd be overnight and didn't want to start a fire.
Thoughts on stuff like &quot;reflectix&quot; liners for the enclosure that would help retain heat, small heaters, IR lamps, etc...?  All preferably on the cheap side.
The easiest step would be to add some isolation on the outside of the box. If you have space inside, there might be a good spot to store some non-flammable insulation, for example rock or glassfiber wool.
A different material might also be possible - firebrick is not only non-flammable but also a very good insulator! about 2-3 inches of firebrick can contain the heat produced by a tempering oven while the outside is cool enough to be safe to touch with gloves.
However, you should install an extra thermosensor for the chamber temperature - and make sure that the printer enters print halt mode once the temperature in the chamber gets above a critical temperature to try to mitigate fire risks and possibly start a chamber-cooling protocol - which might include aborting the print or activating coolers that rapidly cool down the chamber.
As you pretty much are going heated chamber, you might find a spot when you might want to use a flexible hose to pull non-chamber air to supply the parts cooling fan.
Also, possibly relocate as much of the electronics to a compartment separate from the printer's heat chamber to ensure the electronics don't get cooked and can be supplied with cooler air.