Tile coasters make fantastic homemade Christmas gifts.  However, I am not going to re-invent the wheel here. There are a wide variety of tile photo coaster tutorials out there on the web. Google it and you will see what I mean. I learned how to do this way back in 2006 courtesy of my MOPS group. I cannot find the original tutorial online. However, I am happily linking to the two best tutorials that I think match up with my project.

Here's a fantastic tile coaster video tutorial 
(however I do not recommend working with tissue paper, it is very delicate to work with)
Here's another great tile coaster tutorial

My tips:
Let everything dry thoroughly before moving on to the next step.
I used tiles thick tiles from Home Depot, not the classic thin white ones
I used cork on the bottom (adhered with spray adhesive), instead of felt dots
I used Polyurethane coating instead of clear spray paint (they are similar)
These coasters are not heat resistant, but might be okay for coffee mugs...might.

Happy gifting!