I believe you are dealing with composites in your example shots and there is either a significant amount of retouching or these are illustrations meant to look like photography. All plastic and rubber castings have defects or molding seams, there is none of this in any of the samples. The drop shadows are also added in post.
Why I say this:
- The single pump image does not show the reflection of the packaging which would be evident if it were standing next to it as shown. The pump hose and bulb are not reflecting or casting any shadow on the pump cylinder. So they look to be separately imaged and composited in post or simply coloured in post via a Hue/Saturation layer.
- Looking closely at the multi pump images, you can see white highlights around the bulb, this indicates they were close-cut.
- The highlights are exactly the same on each one of the bulbs and bulb valves so I would say these have simply been duplicated.
- The "ring" is clearly close-cut, note the white outline, I would venture to guess this is an illustrated item.
- Notice the white highlight around the silicone base of the blue pump, right upper edge. This would not be evident if these were a group shot since the black pump would be interrupting the reflection.
So that was a quick dissection but doesn't solve your issue for the most part other than you may need to shoot them in pieces and composit them in post. I would approach this with an overhead light source with the product on a sheet of white plexiglass with a light underneath it(note the highlight on the under edge of the silicone base where is meets the plastic pump tube) if you want to duplicate the under light effect. Killing the base highlight where it sits on the surface can solved by adding a circular card, or for that matter adding the highlight in post. Adding additional reflector cards to the left and right front of the pump for edge definition. You will need to gauge your success with your eye at lens position. Adding black cards behind to the left and right of the pump should give you an edge to close-cut them.