How create a cube with a rippled surface I'd like to create a cube with one side rippled in the form of a sine wave.
Here's what I've done so far:

I wrote a Python function to create a sine wave curve
I extruded the curve to form a 2d sine wave
I boolean joined the 2d sine wave to a 3d cube

This results in a 2D sine wave on top of a 3d cube - picture attached.
Instead, I'd like to have a solid 3d object with one side being a wave. Ideally, I'd like to have an object with no internal faces, as I am exporting this into another program that does not deal well with internal faces.
You can just extrude your sine surface second time, and then

scale it to 0 in extrude direction S,X(Y or Z), 0



In my gif I also recalculate normals at the end.