Oh, well with siblings that old then there's no way to try and get it easier with your mom by offering to watch them - they're a-ok on their own so try to do some things "for the family" on your own.
And I figured as a student you were probably broke (I was!) and wouldn't have necessarily been able to get things.

And I wasn't suggesting it due to wanting to actually make her something - just as a way to get some undisturbed time. And I figure, with your mom seeming to be quite selfish, that saying it was for her would lead to a slightly more likely chance of being left in peace to do it.
I honestly wasn't suggesting anything at all because I thought it would help repair your family - I figure that it's just not happening (as is how things are with me and my family). I also didn't really think they'd be enjoyable activities. Just the things I could think of that could be possibly seen as "helpful" and not as "selfish" (I was thinking of my own mom really), and then trying to twist them around and adding things to make having the activity interrupted as little as possible (like... taking the younger siblings being seen as giving your mom time to herself, vs getting yelled at for being out of the house too much. If your siblings were younger it'd have worked well!)