# Mask, invert extract shell

**URL:** <https://forum.nomadsculpt.com/t/mask-invert-extract-shell/1785>\
**Category:** Feature Request\
**Created:** [March 1, 2021, 7:29pm UTC](https://forum.nomadsculpt.com/t/mask-invert-extract-shell/1785 "2021-03-01T19:29:59Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Robbie\_Morris](https://dub1.discourse-cdn.com/flex005/user_avatar/forum.nomadsculpt.com/robbie_morris/32/471_2.png) [@Robbie\_Morris](https://forum.nomadsculpt.com/u/Robbie_Morris)\
**Post date:** [March 1, 2021, 7:29pm UTC](https://forum.nomadsculpt.com/t/mask-invert-extract-shell/1785/1 "2021-03-01T19:29:59Z")

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Not sure if possible but it’d be nice if you could invert the shell when masking. It would preserve the outer but give a hollow density wall.

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**Author:** ![stephomi](https://dub1.discourse-cdn.com/flex005/user_avatar/forum.nomadsculpt.com/stephomi/32/19583_2.png) [@stephomi](https://forum.nomadsculpt.com/u/stephomi)\
**Post date:** [March 1, 2021, 10:05pm UTC](https://forum.nomadsculpt.com/t/mask-invert-extract-shell/1785/2 "2021-03-01T22:05:27Z")

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I could allow negative thickness.

Also I add an “engrave” option where the outer surface would be “pulled backward” so that the new extracted piece would “fit”.

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**Author:** ![stephomi](https://dub1.discourse-cdn.com/flex005/user_avatar/forum.nomadsculpt.com/stephomi/32/19583_2.png) [@stephomi](https://forum.nomadsculpt.com/u/stephomi)\
**Post date:** [March 2, 2021, 7:28pm UTC](https://forum.nomadsculpt.com/t/mask-invert-extract-shell/1785/3 "2021-03-02T19:28:39Z")

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> <https://twitter.com/nomadsculpt/status/1366827080571322375>