make some Cat shelves out of wooden pallets and carpet off cuts

Cat shelves are a great way to build some enrichment into your space and empower your Cat(s) to have some agency. You don't need to be a carpenter or buy any materials to make shelves. With wood glue or a nail gun, a jigsaw or handsaw, and found materials like wooden pallets and found textiles like carpet, you can easily make some shelves. If you need tools, there is likely a free tool library or a friend who has a saw. It's a more ambitious "free" thing to do for your Cat(s), but it might end up being fun for both of you.