Reconstructing curves from STEP

The PDF is largely useless, except to somebody with a CAD program.
The step file imports into SOLIDWORKS without any trouble (see screenshot). The screws are missing from the imported file, but that seems easy to fix.

What is going wrong when you import the step file? I just drag/drop, and it works fine.
There is no feature tree to work with or modify, so modifying the parts will be a bit limited.

I think there is a program that is meant to allow you to stretch/pull imported geometry to the desires shape. I can never remember the name though. I'm not sure how it would do on curved models. I'll try to recall the name.

Here is how I did the outside of the model. 8mm seemed like a huge amount for this model, so I assumed it would be done 4mm to each side.
The interior would be done in a similar fashion. It would be a bit more complex as the bosses and other features will have to be extended to reach the new floor/roof.

Let me know how this compares to the trick you are testing.

Another option is using Split, moving one model out the desired distance, then filling in the gap.
I think both methods can work, but a lot comes down to how the final part/assembly needs to look, and the volume of space within.

SW2017 file attached. Step as well.

Thanks for your extraordinary help Fred. 8mm is too much, right but the housing will be used for testing and the battery I have is 10mm. I have couple of eletronics boards that come in there too.

What I did was: Recontrsuted the base geometry with the help of PDF and STEP file and imported the STEP file into Solidworks and did 3D sketches and converted the entites and copied it to the new file. I did the necessary changes and the result is close to what I expected. :D

Thanks a ton for your inputs. Always helpful.