How were these float components made ?

[Gregory Perkins]

Obviously the cap is glued and or screwed to the bottom of the float but as composites, how were these two halves made ? There is no bottom mold I can think of that could make the bottom part of the float unless it was a clamshell that separated in two pieces to dump the bottom float component.
Sort of like bullet molds that you pour molten lead into.

 

[Flatiowa]

 

[Chopndrag]

 

[Gregory Perkins]

 

[Chopndrag]