Your description above is not nearly enough for someone else to make it to your satisfaction.
How to proceed:
1. Obtain a good CAD application. Autocad, Rhino3D or similar.
2. Spend a few hundred hours getting familiar with the application.
3. Draw out, on paper, a general layout
4. Decide how you want all the panels connected. Rivets, bolts, brazing, welded
5. Decide on a material. Steel, alu, plastic, some combination
6. In your CAD application, draw each individual panel.
Screw holes, attach points, panel thickness, ATX standard for the PSU, motherboard, I/O panel, cooling vents, etc, etc.
7. Refine and redo it dozens of times, until you are satisfied.
8. Find a shop, either local or online, that can cut those panels out of your chosen material
9. Discover what file format they require
10. Redo #6, because the engineer tells you that is not workable.
11. Pay lots of $$$
12. Receive and assemble.
I estimate a year of dedicated work, minimum.
EDIT: Add Step 13: Cry when the actual airflow through the case is not even close to what you really need.