Shapeways stores all prices and performs all calculations in USD and then converts to EUR for display in the shops with the appropriate rate. Thus the eur prices and the markup you receive will vary over time with the rate.
Are the Shops in USD or Euros. - this is a real Hodge-podge affair! When I go into Shops the prices are in USD, only from /shop, when I click "View public shop" are the prices in euros.
People in the EU should see the euro price, everyone else should see the dollar price. I presume that they sort people by their IP address.
In any case, it should be consistent. I see everything in eur (I am in the euro zone) except on the spreadsheet, which uses dollars. (But which does not seem to show vat correctly. Oh well...)
The normal form is to let the viewer of the shop choose the currency they want quoted: with a refresh of exchange rates when the selection is chosen.
The default is based in IP, but later based in address you have stored and finally the one you use for an order. Which means the system can change and even get confused as you click around the site. To make it "funnier" Euro is the default for Europe and part of Asia (that or Kazakhstan has been teleported), when it only makes sense for "eurozone" (17 countries of EU) to default to euro.
O'k I like it: you correct the IP address with the home address entered for the shop. Great! So the sooner you adopt UK Pounds for my unique items into a unique market, the better. This has serious ramifications in marketing at a price that is familiar to customers. (The UK Pound is still the reserve currency for 11 countries around the World.)