Glen, here in the UK, selling a Silver item with a printed hallmark carries just the same criminal implications if not more so. Rapid prototyping and 3D printing for silver was how I found Shapeways... the same thoughts went through my head and I checked it out, but for us Brits, thats a no go
For countries that have signed up to the International Convention Standards, any member county's hallmarks are good in another member's country. For the UK, any item bought as a 'personal commission', i.e. me buying my own models in Silver from Shapeways doesn't need a hallmark, but technically under UK law, if a Silver item is sold through my Shapeways shop to someone in a member country, then that item would require the appropriate hallmark under UK law (Dutch or British hallmark.) - The only workaround I can forsee on that side of things is if Shapeways was a 'Members Only Outlet' and all models were 'Private Commissions'
For me, re-selling Shapeways Silver items over 7.78g (~0.7cc) from Shapeways would need the items to have a round trip to the London Assay Office to be assayed and stamped. This roughly doubles the cost price of a 1cc item, adds 35% to a 2cc item, etc.
Having said all that, I'm looking forward to next week when I can sit down and order some Silver for myself
For those going to the Newcastle Maker Faire - see you tomorrow