You can, but it rarely saves money. Interior designers understand how a home should flow functionally, and they manage hundreds of decisions — from grout line thickness and countertop edges to transition points and adhesive types — that most homeowners don’t anticipate. Without that experience, homeowners tend to redo work they’re unhappy with, which often costs more than hiring a designer would have. If you do design your own project, every detail must be fully specified before construction can begin.