Paper sticks for masks: When making masks, a lot of the time, children don’t like elastic round their head, plus you might not have any. Instead, roll an A4 sheet of paper tightly on the diagonal (a cocktail stick can be useful to start it off and make sure it’s tight enough, pull it out once you’ve started rolling). Tape it up and you have a relatively strong stick to tape your mask to. I’ve alo used these for lightweight mobiles.
Sensory tubs: Cat litter trays are a very cheap small solution, or underbed storage, the huge advantage with those is that you can pop the lids on and move them to the side if you want to put the activity on hold for a bit. I must admit that there’s been a box of popcorn, one of cloud dough and one of breadcrumbs stacked in my carport for the last 5 months! Tuff trays are something a lot of people love, I don’t have one, but am very tempted, you get them from builders’ suppliers, the advantage of these is that they are large enough for a child to sit in with the sensory materials (though mine will sit in any container I use, no matter how small).