...Acrylic glass, screws, hinges, hasp& staple, and wood.
As DD1 is now the escaping and climbing performer, we have tried to foil her wyley ways.
My Dear Father has lined the bannisters with Acrylic glass, so that there is nothing to climb on to reach the newel post.
He has also fitted a hinged wooden bar across our laundry cupboard, so that when we have it shut, the girls can't pull out the laundry tubs. If DD1 can't pull the tub out, she can't stand on it. If she can't stand on it, she can't climb over the stairgate