Extend mid-section of BRep

[zero1tango]

What steps do I need to do to extend the mid-section of a BRep made from an STF (original design file not available)?  I would like to extend a cross-section of the approximate area shown by 3/4 in. in the direction shown in the screen shot.  Basically, it's for an enclosure that I need to enlarge a bit.  I got as far as the STL/BRep conversion but hit the wall at slicing and whatever else is involved.

[laughingcreek]

it would be better to remodel this in fusion.  then you would have complete control.  brep's converted from stl files frequently behave badly

but-

-you place a construction plane  OR draw a sketch line at the desired split location nd use one of those ojects to split the body with the "split body" command.

-move one half down by the amount you want to extend the object

-extrude one face to the other.

attaching your model would help in answering your question better.

[zero1tango]

Thanks for the response @laughingcreek   STL file of model attached...

[laughingcreek · Accepted solution]

here's a screen cast (and resulting model) of a possible workflow.  the process is complicated by the unfortunate alignment the object has with it's origin.

https://knowledge.autodesk.com/community/screencast/d3335ca6-0328-4125-b7e0-b7b38640b25e

[zero1tango]

Thanks, @laughingcreek!  I really appreciate the time you took to develop the workflow to modify the STL model.  Ultimately, and partly because I discovered that I needed to add a new internal feature, I took your advice to start from scratch.  FYI, I attached the new shell file.  The front and back faces will be separate objects that will be attached post-print because of printing and other fabrication issues.

Thanks again.  Stay safe and make stuff!