David's instructions work correctly.
Here's the deal: if you extrude along the y-axis, then you want to rotate about the x axis. Put:
ROTX ang
at the top of your 3D script, where 'ang' is the slope angle as measured in your section. Since this is a 1-off object, there's no point getting fancy and making it parametric.
You will not see the result until you rebuild the 3D view.
(Similarly, if you extruded along the x axis, the you want a ROT Y.)
After you've created your extrusion, select it, press command-shift-O to open the object, click on the 3D script, insert the line indicated above, and close/save.
Karl
One of the forum moderators
AC 28 USA and earlier • macOS Sequoia 15.2, MacBook Pro M2 Max 12CPU/30GPU cores, 32GB