Despite the financial crisis and the housing slump, the phone is still ringing in Peter Gluck’s office. “We’re OK for now,” says Mr. Gluck, whose office of 50 architects specializes in high-end residences costing $5 million and up. That may be explained by the fact that Mr. Gluck and his associates aren’t just architects for their homes. They’re the general contractors as well, unlocking gates in the morning and stepping onto scaffolds to direct construction.