# Using “Union” **URL:** \ **Category:** Modeling Questions\ **Created:** [November 2, 2018, 4:05pm UTC](https://discourse.shapr3d.com/t/using-union/3133 "2018-11-02T16:05:29Z")\ **Posts on this page:** 3\ **Page:** 1

**Author:** ![Leroy](https://avatars.discourse-cdn.com/v4/letter/l/e0b2c6/32.png) [@Leroy](https://discourse.shapr3d.com/u/Leroy)\ **Post date:** [November 2, 2018, 4:05pm UTC](https://discourse.shapr3d.com/t/using-union/3133/1 "2018-11-02T16:05:30Z")

I am a retired, part time hobbyist with limited knowledge. I really have enjoyed making stuff with Shapr3D, but sometimes I get stumped. When drawing my shape, there are a lot of individual parts the can be extruded separately. Do I have to use the “union” function to get them all to stick together so it prints well? I have had a couple errors - “Target or tool is a general body” “Non-manifold body” I am not sure what they mean or what to do. Or even if it really matters ? ---

**Author:** ![DanielR](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/danielr/32/582_2.png) [@DanielR](https://discourse.shapr3d.com/u/DanielR)\ **Post date:** [November 2, 2018, 4:09pm UTC](https://discourse.shapr3d.com/t/using-union/3133/2 "2018-11-02T16:09:42Z")

Hi- glad that you like the app. These error messages mean you have created non-manifold bodies: [https://transmagic.com/what-is-non-manifold-geometry/](https://transmagic.com/what-is-non-manifold-geometry/). If this happens the best thing to do is start over again, as you unfortunately can’t undo this with any boolean operations. ---

**Author:** ![Istvan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/istvan/32/23668_2.png) [@Istvan](https://discourse.shapr3d.com/u/Istvan)\ **Post date:** [November 2, 2018, 6:13pm UTC](https://discourse.shapr3d.com/t/using-union/3133/3 "2018-11-02T18:13:22Z")

Can you post a screenshot?