Draw about 8 new pentagons on cardboard, just like the ones you made in Step 2.
The number of pieces you need for the base depends on how thick your cardboard is and on how thick the base of your bulb holder is. For this reason, make sure to make some tries with it. You may need to remove or add some.
When you are sure of the number of pentagons you need, draw a smaller pentagon in each of them, at about 1cm (0.39 inches) from the border.
Cut everything using a cutter, removing the central part.
What you'll obtain is new equal pentagons.
Glue them one above the other with white glue (or hot glue), making sure to match their angles and sides together this time.