If your flying here and its checked luggage, and its returning with you, it is less of an issue.
If you are shipping it here....
Prototypes when they come in have to leave within an agreed time period or be destroyed. And periodic checks are made when declared as a prototype, once its in the states. Your customer faces a serious issue if it does not leave or is not destroyed.
Either it is an approved device with a an approved variance, with the variance number label on the product, as well as an having an assigned accession number or bonded as a engineering sample, or it is not legal for import...
If it has no laser in it, its just a toy gun... Some states such as NY, NJ, CA, VA, MASS, and the Transportation Security Administration have laws/rules regarding realistic looking toy guns as well...
You either go thru the full procedure, or remove the laser(s), or your breaking the law and its subject to seizure...
The variance form is not that hard, but you will have to add certain safety features and your customer will need their own variance, prior to purchase.... Which I really wonder if it would be issued at all, unless the customer is a laser show company, professional entertainer, or a movie studio.
One way or another it is considered a Demonstration Laser Device (Old name for pointer)and perhaps not a legal one...
Steve