After cutting and filing all of those panels out, you will either want to stop building forever or feel great about your accomplishments. If the later is true, its time to move on to mounting the holoprojectors. To do this, grab your drill, countersinking bits and some hardware. I went to Lowes and picked up some 4-40 x 3/4 flat machine screws. These are found in the drawers and come in packs of 5. You will need three for each HP. Don't forget to get the 4-40 hex nuts to go with them.
Take the ring and place it through the hole for the HP you made on the inner dome. Use a pencil or marker and mark the three
Remember to double check where your holes will be before you drill them. Around the top holoprojector, if you drill a hole on the top side it will show through. Not a big deal, but easily avoided.