I have a basic model inkjet printer, and my guests have to sleep in my PC room only. I am supposed to take printout in midnight only. I tried to control the heavy noise during printing by using the dust cover that came with it. But it did not help. What else can I try?
Insulators will certainly help.
Try wrapping the noisy parts with a blanket or noise-reducing mats and taping them there to reduce noise. A sound-reducing blanket could look like this:
Attaches with Velcro, so your printer won't look so weird with all the tape... Amazon will probably sell some stuff that are flexible and can reduce noise. Using insulators like blankets should help you out. A giant jacket could cover the entire printer, just open the zipper to get the papers out of there.
Otherwise, you could buy a newer printer that is quieter.
Instead of making the output directly to paper, you could set up a PDF printer and make the printout at midnight go to the PDF printer. And then you could make the paper output at daytime not disturbing your guests. (Or even better, just store the PDF output and save paper :-) )