# Modeling question: How to achieve smooth transition between solid body and closed end surface for a bike saddle?

**URL:** <https://discourse.shapr3d.com/t/modeling-question-how-to-achieve-smooth-transition-between-solid-body-and-closed-end-surface-for-a-bike-saddle/41661>\
**Category:** Modeling Questions\
**Tags:** discourse, featured\
**Created:** [September 19, 2026, 5:25am UTC](https://discourse.shapr3d.com/t/modeling-question-how-to-achieve-smooth-transition-between-solid-body-and-closed-end-surface-for-a-bike-saddle/41661 "2026-09-19T05:25:15Z")\
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**Author:** ![margriet](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/margriet/32/36415_2.png) [@margriet](https://discourse.shapr3d.com/u/margriet)\
**Post date:** [September 19, 2026, 10:14am UTC](https://discourse.shapr3d.com/t/modeling-question-how-to-achieve-smooth-transition-between-solid-body-and-closed-end-surface-for-a-bike-saddle/41661/2 "2026-09-19T10:14:11Z")

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You might want to try a different approach instead of lofting the end separately and then using Union.

I recently used a similar technique in the **Extrude 4/5 Challenge**. The sloped transition on the base looked quite complicated, but the solution turned out to be surprisingly simple: I created two larger solids and used **Intersect** , so the required transition was created by the intersection of the two shapes.

Perhaps the same principle could work for your saddle. Instead of trying to blend two finished shapes together, you could extend the main body, create a second smooth solid that defines the rounded end, and use **Intersect** to create the transition.

It’s not exactly the same geometry, of course, but the Challenge made me realise that sometimes it is easier to let the intersection create the transition than to model the transition itself. Perhaps it help you. I am also curious what others will say!

This is the Challenge example I mean:

> [@Season 2 Challenge #4 is DONE | Extrude 4/5](https://discourse.shapr3d.com/t/season-2-challenge-4-is-done-extrude-4-5/41573/26):
>
> My first submission. I learnt about how to cut a cone into 3 separate bodies, which was very useful

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