What's good for sticking plastic stools?
Tie it with 502 sticky or rope. If you don't have rope, you can buy some wires. I know you want to save. But I think safety is more important than saving. So it's a good choice to buy a new one
Buy epoxy glue, this kind of glue can even stick to iron, but pay attention to using it
Neoprene, epoxy resin, acrylic glue (502 glue) and so on