| CPC B29C 64/393 (2017.08) [B29C 64/00 (2017.08); B29C 64/112 (2017.08); B29C 64/386 (2017.08); B33Y 10/00 (2014.12); B33Y 30/00 (2014.12); B33Y 50/02 (2014.12); B63H 16/04 (2013.01); G05B 19/4099 (2013.01); G05B 19/41885 (2013.01); G06F 30/20 (2020.01); G06T 19/20 (2013.01); B63H 2016/043 (2013.01); G05B 2219/32359 (2013.01); G05B 2219/35134 (2013.01); G05B 2219/49007 (2013.01); G06T 2219/2016 (2013.01)] | 17 Claims |

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1. A method of fabricating a three-dimensional object, comprising spreading powder material on a tray to form a plurality of layers, each powder layer comprising a configured pattern corresponding to the shape of the three-dimensional object, wherein for each layer the tray is lowered to form said layer at a predetermined thickness; and
wherein a post-formation shrinkage of said powder layers along a vertical direction is compensated for by:
i) lowering said tray by a different step size for different layers, wherein determination of the compensated slice data assumes layers of same thickness; or
ii forming each layer from compensated slice data, wherein determination of the compensated slice data assumes layers of different thickness; and wherein said tray is lowered by a constant step size for different layers.
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