13 kg is not too heavy for shipping.
Can you call UPS and ask them for a quote?
If it is not too expensive, I am interested.
you could pack it first with some foam or bubble wrap and cardboard around it.
And then into a larger box with lots of protection.
UPS is usually a good carrier from the UK to Germany and reasonable prices.
Maybe you find a way, so Zucca does not have to come over from the US.