Another way to change the current pattern if your Tool options dialog is not showing: open the Patterns list dialog, either
with Windows ➤ Dockable dialogs ➤ Patterns
by clicking on the pattern preview in the toolbox (if showing, this is set with Edit ➤ Preferences ➤ Interface ➤ Toolbox ➤ Appearance ➤ Show active brush, pattern and gradient)
You need to convert the graphic to a combined path first.
Ungroup it until there are no groups left, select all of it and click Path > Combine.
Now, copy it
Add the pattern along a path effect, then in the path effects, set to "Repeated".
Illustrator's 3D effects are underpowered for drawing the wanted plate number 2 easily. With a 3D program one would make it in few minutes and any viewing direction would be as easy.
Drawing it in 2D from scratch (=not importing from 3D) is, of course possible, but the plate should be seen to be sure how it should be drawn.
To see it I made this in a CAD ...
I'm writing an answer for 2nd type of plate inspired from Billy's answer and joojaa's comments.
Create a stroke and apply Effect > Distort > Zig-zag effect and then apply Effect > 3D > Extrude & Bevel. Expand it.
Rotate it and crop/clipping mask it to create a rectangle with different angle (to apply clipping mask, draw any shape above the ...
I've no idea what the rightmost drawing is supposed to represent. Sorry. However, it's easy enough to make a wavy plate/surface using 3D Extrude and Bevel. The shape on the left is straight line, with a Zig Zag effect applied, then Expanded to make a shape to use for the 3D extrusion.
It can of course be rotated to any desired angle