The coaster part of the project had been bugging me all the way through this project but I thought I would figure it out when I got to the end of the project. I needed this part to be strong that's why I used an 3mm think piece of aluminium which was over kill but I wasn't taking any chances. I also decided to use a 2mm thick piece of perspex because it had to be see through. I also needed this part to be water proof because as we all know condensation forms on the outside of a ice cold drink. I was thinking of using bolts and tapping the aluminium on the button to sandwich the WS2812 LED's between the layers.

I had a stroke of genius and decided to use some clear silicon adhesive because this would make it water proof and stick it all together without having to use bolts and taps

Here it is with a heavy weight to make sure its stuck well