I have ordered several items from Shapeways and am always amazed at the relatively high postage and packing costs. Recently I ordered a few items within days of each other. Unfortunately as there is no combined order function I was charged separate post & packaging although they would all have fitted in the same box. I realize the items must be carefully packed but the boxes used are always far larger than necessary. It would be nice and more professional if there was a way to combine the orders as 8 to 10 euros for each grossly over sized box is far to expensive. On some of the orders the Packaging & "Tax" etc costs are higher that the production costs which is very off putting.
As Minime suggested, next time email service and they may be able to combine your orders and not charge you for the additional shipping. Also we have a supply a few sizes of boxes, that we use for all items. So your items probably wouldn't have fit in the next size down box. Our shipping will seem high if you order only a few small things, but seeing shipping is a flat fee, you could order large items, or a large number of items, and the shipping will remain the same.
Also some of my customers have this problem, It's not nice if the shipping price is higher than the price of the model