Thicken faces of an arbitrary polygon

I need to make an extruded spiral with gaps in between each "round".
I managed to make one with the following code:

```
radius = 1.0
num_rounds = 5
height = 1.0

pts = []
gap_size = radius / num_rounds
for angle_deg in range(360 * num_rounds):
angle_rad = math.radians(angle_deg)
radius_shortened = radius - (angle_deg / 360.0) * gap_size
pts.append((radius_shortened * math.cos(angle_rad),
radius_shortened * math.sin(angle_rad)))

result = cq.Workplane().sketch().polygon(pts).finalize().extrude(height)
show_object(result)
```
Giving something like this

However, now I'd like to thicken the "walls" of this spiral, but I have no clue of how to do this.

I've tried many things like concatenating many boxes to make this spiral with the thickness I wanted, but without success.
I've also tried to do it with polylines rather than polygons, but I have to ".close()" the line before extruding, and it has an unwanted wire/face in the end.
I've seen that one could do .thicken() on a cq.Face(), but I don't know how to extract a cq.Face from a Workspace.

Any help would be much appreciated, thanks!