Haw. Rev. Stat. § 554B-3
A custodial trust may be created upon the occurrence of a future event. The person having the right to designate the recipient of property payable or transferable upon a future event may designate in writing a custodial trustee to receive and hold the property for a beneficiary of a custodial trust to be effective upon the occurrence of the event by designating the recipient, followed in substance by the words: "as custodial trustee for ______________________________ (name of beneficiary) under the Hawaii Uniform Custodial Trust Act". Persons may be designated as substitute or successor custodial trustees to whom the property must be transferred in the order named if the first designated custodial trustee is unable or unwilling to serve. The designation may be made in a will, a trust, a deed, a multiple party account, an insurance policy, an instrument exercising a power of appointment, or other writing designating a beneficiary of contractual rights. The designation must be registered with or delivered to the fiduciary, payor, issuer, or obligor of the future right.
HRS § 554B-3