Your model should have a strong and obvious base/bottom

All Shapeways 3D Printed Ceramics need to be glazed. While it's being glazed, or toasting in the oven, it needs a base to support it. Pieces with a clear base will be much more likely to glaze than pieces without. For pieces without a clear base, we have support structures, but the support structures might leave small dents in the surface of the glaze.

These bunnies have a clear bottom.	This bowl also has a clear bottom

Pieces without clear bottoms will be put on stilts, think of it as tiny claws that hold up your piece while it is in the kiln. Because the support only touch the object at a small point, it minimizes the disruption in the glazing process. However, the point still creates little "craters" in the glaze surface. 



To avoid this, make objects with a clear base, a clear surface the object rests on. 

Holes must be minimum of 3 mm, and the wall the hole is in should be no greater than 10 mm thick.

Small holes can be problematic when 3D printing ceramics because it is difficult to get the powder out. Also, when glazed, smaller holes will seal in the glaze. For decorative holes, this could be OK. But for functional holes (ie loop for a necklace). If you have a straw with a small opening, the hole will not be able to be de-powdered. 

Edges should be smooth (no knife edges.

The jagged edges will fall off during de-powdering

The dimensions of an item's bounding box must add up to a minimum of 120 mm

To ensure that all models are glazed properly the minimum bounding box for 3D printed Glazed Ceramics must add up to 120 mm, so you can still print thinner tiles and more square-ish models. Pieces that are smaller than this are incredibly difficult to glaze reliably. Also, small pieces tend to lose all their details in the glaze process.

Pieces that "fit" together are tough, but if you have to design this please keep a clearance of 4 mm.

For pieces that fit (ie teapot lid and teapot), the clearance between the designs should be 4 mm. This is because the glaze will add up to 1 mm of surface volume in some places. To ensure that your piece still fits, please keep a 4 mm gap between the two pieces.

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