For Mr. Round and Ms. Kordos, being their own general contractors has given them a similarly hands-on connection to the handiwork of building. They made their kitchen counters, for instance, out of plywood, and recently gave them a coat of high-gloss white paint. (It’s a placeholder, Mr. Round says, but for the moment it looks great.) It steps down from the kitchen island to form a built-in table, good for meals, snack time and crafts. Underneath the counters are a series of Ikea cabinets in three different finishes, mostly bought on sale and installed, like with like, in coherent blocks.