i searched google for "5cm shiny orange plastic piece" and "5cm shiny jet black plastic piece" images, and the results were invariably things that would not be reconstructed well via photogrammetry due to the lack of surface texture.
have you had success with non shiny-small-plastic pieces? If not, then i suggest that's where you start, because shiny pieces are notoriously difficult and so are small pieces, so small shiny pieces are going to be even harder.
If you're sure that your photo quality is not the issue, and that you are getting sufficient detail, and that you are doing the masking things correctly, then i would suggest you increase the number of photos, maybe even hundreds as opposed to dozens, so that each one has a greater chance of matching with an adjacent similar looking one, which may have been why the video thing worked.
Other general things to try include adding a non small-shiny thing in the scene to help the software find matching points, such as a sheet of newspaper underneath. Make sure the frame is filled as much as possible with your object as opposed to the background. Also try adding more light or working outside rather than increasing exposure time.