In a city where a debonair gent can count modish custom suit designers on one hand (one finger?), Commonwealth Proper is working against the stats, one three-piece at a time. Attorney Craig Arthur von Schroeder launched his collection of slim-fitting, limited-edition men’s button-downs last year. (Find them at Old City’s Matthew Izzo. A few months ago, he added made-to-measure suits to the line. Von Schroeder, who works with tailor Jay Tidwell and business partner-wife Amy Apollo, sees clients in an industrial loft in Northern Liberties and, beginning this month, a by-appointment-only showroom at 2200 Walnut Street. The customers: new graduates seeking their first bespoke basic navy suit (a less-than-$1,000 outlay), future grooms buying the tux of a lifetime, and professionals ordering a go-to ensemble (big this season: herringbone or classic glen plaid from Holland & Sherry). The philosophy: Invest in made-to-measure now. Be dapper tomorrow. (Or, in eight to 10 weeks.).