Sledgehammers poised and ready to strike, David Levinson, chairman and CEO of L&L Holding Co., together with some of the team that's helping his company redevelop 200 Fifth Ave. enjoyed a recent sledgehammer party on the property's second floor. The event marked the commencement of the $100 million renovation of the 800,000 s/f former International Toy Center at 23rd St. into a class A office building.