AN ART COLLECTOR’S Penthouse by Maho Abe of Zen Associates, with David Glod, builder. by LOUIS POSTEL March 2007, originally published in BOSTON MAGAZINE (photography by Richard Mandelkorn). In a Cambridge penthouse, master cabinetmaker Paul Cusack carefully buffs a black lacquer credenza that he made 21 years ago and jokes with the homeowner about “lifetime guarantees.” He is fixing the…