I've uploaded a model made in Blender, and it passes all the tests and can be carried all the way through to checkout. My question is; is the model hollow or a solid lump? It's exported directly from Blender as an x3d file. In Blender it's a mesh object. I really have no experience at all with 3d printing (and not that much more with modelling in Blender to be perfectly honest). Maybe as some additional indication as to whether it's hollow - the quoted cost for full colour sandstone is â‚¬31.53 (about $43), for a model of dimesnions cm: 3.736 w x 4.996 d x 3.682 h. My worry is that as I don't know how thick the walls are it may be very weak, and I'd like to get it right before ordering something to ship to the UK. Any feedback or answers appreciated. Thanks, Scott.