Tips for a cheap draft cover that nobody talks about

I did something similar with mine but went sideways instead of up. The J1 box had these thick foam corner blocks and a big sheet of that dense grey packing foam, so I cut the foam sheet to fit the back panel and taped it there with gaffer tape. It's been on since about March and it's dulled the room temp swings enough that my ABS brims stopped lifting on cold mornings. I print in a garage that dips to single digits overnight, so even a small buffer helped. I never tried the air columns as a curtain because mine were all punctured from the journey, half of them flat. Sounded like a puncture test every time I walked past the printer. The foam is less effective per cm but it doesn't melt anywhere near as easily, which matters since I clipped a shelf bracket once with a 180mm tall part and had to rescue the print halfway through. One thing I'd add is that the foam also quietens the whole thing a bit. Not much, but the enclosure rattle I used to get from the side panels is basically gone now. My wife approves, which is the real metric in this house.

I actually tried using some of the shredded styrofoam bits that come in the corner of the printer box. I used them to pad the inside of the print bed and underneath the motion rails. I wasn't trying to stop drafts, but the whole thing felt really shaky during long prints. The packing foam killed the micro-vibrations that I thought were just the stepper motors running. It made the finished parts feel much tighter because they weren't vibrating on the build plate. It was a wierd fix, but it made the biggest difference for my final results.

I have to call doubt on the foam fixing the rattle thing. If your side panels were rattling, that's loose screws or the panels not seated in thier grooves properly, not a noise problem you can tape foam to the back to solve. I chased the same rattle on mine for weeks and it turned out one of the corner brackets had backed off half a turn. Tightened it and the noise went away completly, no packing material involved. The insulation part of your post I buy, but I reckon you'd have the same quiet garage either way if you just checked the fasteners.

Same here with the air columns, I kept mine too. Agree with the melting warning, mine got too close to a tall ABS part once and it shrivelled up with a smell like burnt plastic that lingered for days. What worked for me was swapping the tape for binder clips on the frame, so the whole curtain lifts off in ten seconds before anything tall. Also found the flat punctured columns still work fine cut into strips and laid along the bottom gap under the door, they block the draught that comes in at floor level where my warping always started.

I ended up looking into that rattling thing some people mentioned. It turns out I just needed to check if any screws were loose or if the frame panels were seated fully in their grooves. Once I chased down a couple of minor adjustments and tightened the bolts, the movement noise stopped completely. It seems the structure needed sorting before I even started thinking about the thermal shielding.