Hello, I work for a German freight company I'm the USA
I suggest as follow. If he is not bringing enough, and can carry it, might as well checked it as luggage, and insure it. If a lot, then look for a local international freight company. They can assist you with packaging, shipping, customs, and delivery to his foreign address. Cost is variable, depending on weight, and there will be accessorial charges in Germany. It is cheaper to send it by ocean, but it will take time. Transit time from USA to Germany can take at least 2 weeks.