This is one of those questions where there isn’t a one size fits all answer. At www.sdretirementplans.com we create checkbook controlled self directed 401 k plans. A self-directed 401 k plan does NOT require a custodian. Our clients are the Trustees of the plans and make all the investment decisions. We try to make it easy for our clients to administer their plans, explaining the rules etc. It is not as intimidating as most people think.