Large Canvas (Catonsville)

Hey all, happy summer! While my niece is visiting I’d like to do the whole “fill water balloons with paint then throw darts at them” to make art, activity. I’ve got the balloons, paint, and darts. All that’s left is the canvas. I’m lookin for something on the larger side, or multiple medium canvases that are the same(ish) size. I’m happy to recycle any unwanted/unfinished canvases. Please and thanks!