cats

Give her some privacy. Put the box underneath something like a table and Jimmy up some curtains for her, or clean under the bed and put a smaller box under there.

Everyone has given good advice, but I just want to remind you:

it’s kinda dusty and feels like a bad place for babies

They evolved to do this without much human intervention in all kinds of outdoor conditions. Have their lives been improved by domestication and human watchfulness, yes, absolutely... but they'll be okay. A little dust will not be a serious hazard.

It's kind of you to care so much.

Picture is just a bit after birth! Fresh clean towel have been provided every couple of days

Could be Momma doesn't feel as safe in the box as under the bed. I'd suggest cleaning as best you can under the bed without the vacuum, and placing the blankets there.

Another box as suggested could work too, but may be unnecessary if she's already decided that under the bed is safe.

I know you want to watch the little ones, but at this stage it's best to leave Momma to it until the kittens are old enough to start exploring on their own. She may even bring them to you to babysit while she gets some alone time for herself.

Kitten Lady has some good advice for nesting. And amazon affiliate links, but ignore those. http://www.kittenlady.org/mama

Add a clothes /towel roof

Cheaper than that ..she might sprout a 7 th devilished kitten