Driftwood, twine and LEGO Duplo bricks makes a great mobile!
My son Albert is now 13.5 months old and is close to walking by himself. I got the idea to make a mobile and hang it on the wall so that he can reach it when standing. If he pulls one of the bricks, it’s simply released from the other brick. Thus the LEGO Duplo mobile does not get destroyed, we just have to fasten the bricks again if they’re pulled down.
Also check out the Hama bead + driftwood baby mobile