We made homemade slime yesterday... a fun thing to play with for HOURS and HOURS (and hours)! (As she plays at the table I can actually cook dinner peacefully. Sweet action!) You probably have the ingredients around your house already, so you can make it on the cheap. And if you don't have Borax on hand, it'd be worth purchasing anyhow. It's not expensive, and you can make your own homemade laundry soap with it.
Found on Pinterest.
p.s. I'm grateful for my husband who dug the hole and poured the cement for my clothesline.