> ## Documentation Index
> Fetch the complete documentation index at: https://docs.ntop.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Optional: nTop Essentials Challenge Problem

Feel free to try our nTop Essentials challenge problem after completing the optional test problem.

Given the CAD file below, shell the part with a 3mm wall thickness inwards and add a hole for powder removal. Then, mesh the part with a 1mm tolerance and export it as a 3MF. For an added challenge, the hole for powder removal should resemble the shape highlighted below. Your final result should look something like the second image if you choose to create a hole resembling that CAD face.

<Frame>
  <img src="https://files.learn.ntop.com/lessons/working-with-imported-geometry/101_22_OptionalChallenge.jpg" />
</Frame>

**Estimated Time to Complete: 25 minutes**

[101\_22\_bracket.x\_t](https://files.learn.ntop.com/Courses/101%20nTop%20Essentials/Models/101_22_bracket.x_t)

[*Report File*](https://docs.google.com/forms/d/1Ev9UFCZGo1aefglpX6E8sQ6Hr-Y6ILhGSZxE3paCqy4/edit)