How would I evenly shave a component (not the same as scaling)?

[i-make-robots]

I have a complex part meant for a 3D printer.  The printer oversizes outside perimeters by 0.3mm.  It undersizes interior perimeters by the same amount.  I want to run a ... shave command? 

- choose a plane

- all faces orthogonal to this plane adjusted by X distance.  Use ray-casting to find perimeter direction?

This is kind of similar to a shell command, but it works on the outside of a part instead of the solid interiors.

It would also be helpful for my press-fit laser cut designs - I could use a -X to add material equal to the laser kerf.

[TheCADWhisperer]

Can you attach an example file here?

Is it easy to get access to the "interior" faces?

I am thinking 3 basic techniques.

1. Model with these parameters taken into account from the outset.

2. Shell from outside and then Shell from inside (you will need to post file for me to verify this as a possibility). (Depends on having uniform wall thickness parts.)

3. Offset Surface and then Thicken-Cut

or 

4. Model as surfaces and Thicken.

[i-make-robots]

The part already exists, now I need to compensate for the printer.  Doing so at the design level seemed easiest. 

I tried shell, results were not what I expected. 

Offset surface requires that I select every relevant surface, which is a time consuming job a computer could easily accomplish by applying the correct filter.

[Anonymous]

Probably not the optimal way to do this. But this is the way I solved this:

Create an inside shell (Modify -> Shell) with the desired tolerances.

Change workspace to Patch. 

Un-stitch(Modify -> Unstitch) the entire model. 
Delete all outer faces. 
Then stitch(Modify -> Stitch) the whole model again.