How to create an orthosis for a .stl hand? I'm trying to design an orthosis for a thumb for a university project. I have a .stl model of a hand (which can be found here: https://grabcad.com/library/hand--5)
and I'm wondering how to create an orthosis right onto that so that I can 3D print it?
The idea is to 3D scan a random hand, then create the orthosis and 3D print it perfectly fitting. Now I want to try and create an Orthosis right onto that.

Is there a way to select the thumb from that hand model and add kind of an offset to it? My idea would be to create an offset of 5mm or so in order to have a perfectly fitting tube for the thumb and then sculpting that tube into my desired shape.
Is there a way?
I'll upload a picture of a rough solution I made with Geomagic Freeform. I selected the thumb and created an offset which I then shaped to my liking.
However my Macbook is struggling with Geomagic Freeform (and its only a few more days of trial) and I'm wondering if there is a way to create something like that with blender?
I really appreciate your help!
Best regards,
Chris
The workflow in this case would go like this:


In edit mode, select appropriate faces.
Shift+D to duplicate faces.
P>Selected to separate selected faces, then Tab to enter object mode.
Select new object, created from the thumb faces and add Shirnkwrap modifier.Use eyedropper to set hand as a Target for the modifier.
From there you can give the new object shape of orthosis and add Solidify modifier to give some thickness to the model.Somewhat like this: