Where it all started
I wanted something a bit geeky for the house, and I found fibre optics! Using them is very simple, but the results can be great - so once I'd completed my star floor in the bathroom I got hooked, and you'll see at the end of this Instructable some of the other things I've made using fibre.
It is all based on this project by a nice bloke call Andy: https://starscape.co.uk/cp41.html
Fibre optics sound fancy, but what I've used here is just a rod of plastic (PMMA) that looks a little like fishing line. If you shine light in one end, it comes out of the other. The useful bit is that you can bend the fibre, and the light still comes out of the end - creating a point of light - or use several and you have stars!
In just a few simple steps I'm going to show you how I built the star floor. Before starting on the actual 2.5 x 4m bathroom floor I decided to do a trial, and would highly recommend this step, as it gives a good idea of what you are going to have to do (and why) in terms of grouting and fibre management. I used an offcut of MDF as my sample floor, and the smallest cheapest adhesive and grout I could find, along with some fibre, and a makeshift light source. The demo took a few hours to build, with all the fiddling, as well as time in between for the grout and adhesive to set.
You'll also see a capacitive switch I tested, with a view to hiding it behind a wall tile to control the floor by waving your hand in front of the switch.