[JackMcCornack]

There's 50 sets of rules--one for every DMV of every state. Some states are easy, some are hard. In California, 500 people a year get to register their homebuilt car under the smog laws in force at the time that what the car <looks like> was manufactured (a strong motivator for '65 Cobra replicas), and there are states where the easiest way is to include the portion of the chassis that has the VIN number stamped in to it in the new chassis, and register it as an extensively modified Metro. In Oregon it's a walk in the park; it has to be recognizably a car and you need to bring in the receipts for the donor car and other materials (the steel tubing for the chassis, for one example) so the DMV can tell you didn't steal any of it. After that it's between you and the police whether it meets the equipment requirements, but other states will measure your headlight height and count flashes per minute of your turn signals, etc etc blah blah.

PS--Insurance? I insure my homebuilts with The Hartford, the same policy as my ordinary cars. And there are a number of specialty insurance companies that will insure homebuilt cars for less than conventional cars, on the assumption that an exotic car you built yourself is going to spend most of its life in a garage. But mine don't, mine are daily drivers and insured accordingly.