Extrude issue

[Anonymous]

Hi there,

I'm pretty new to using 3d modeling programs so excuse my lack of knowledge! 

I'm currently working on a costume mask to print out and need to add thickness to the object/walls. I've been using the extrude option for this and for some reason it turns the walls of the model from smooth to bumpy/spikey around the model.

Here's some screenshots that will hopefully make more sense!

Thanks!

[hfcandrew]

Usually caused by very tiny triangles at the boundary, or even a non-manifold mesh area.

Select the perimeter and Modify >Smooth boundary

If that doesn't work

Select the perimeter and Edit>Remesh

Also I'd recommend using offset rather than extrude: http://help.autodesk.com/view/MSHMXR/2019/ENU/?guid=GUID-749E6C72-D82B-4FA9-A157-1AE612B779AE

You may get better results. Also I see your thickness value is at 0.15mm. That is still gonna be too thin to print.