Modify Existing STEP CAD File — Extend Part Length (Simple CAD Edit)

I have an existing STEP file (Hilti PMW 71 laser mounting base) that needs a straightforward dimensional modification. What's needed: Extend the part's footprint length from 84.8mm to 114mm Width (71.9mm) and height (45.4mm) must remain unchanged The extension should be added in the plain/uniform section of the body — not through the front notch or the top mounting features Two features must be preserved exactly, in their original form and relative position: A U-shaped notch at the front (~25mm wide x 42mm deep) — clearance for a laser beam, must stay fully open Top-face mounting features (3 rubber pad recesses + center knob/screw boss + hex-key access hole) Deliverable: A native STEP file (.step/.stp) with the modification applied Final dimensions: X = 71.9mm, Y = 114.0mm, Z = 45.4mm Single solid, watertight, ready for 3D printing (HP Nylon PA12 / MJF process) — no internal mechanism needs to be modeled or functional Attachments provided: original manufacturer STEP file, reference photos of the physical part, a written design brief (PDF), and a rough draft STL showing the intended result (reference only, not the source file). This is a quick, well-defined edit for someone comfortable working from an existing STEP file in SolidWorks, Fusion 360, or similar — not a from-scratch modeling job.