OK so first thing first, gather your supplies. You will fist have to use the clay so get it out first. Get about a tablespoon of it out but you don't need to be exact. Roll it into one big ball, well not big, but just one. Have your flat surface ready :)
Now set the ball on the flat surface and press in and down the sides, not alot, but you will have a really ugly lump circle. It's a good thing. Now cut off excess clay on the sides of the lump so it is square-ish. Don't forget to make it dice sized if you had wanted it that way.
Now do the best you can to make it even on all the sides. If you need it more flat than you can get it a bit wet and smooth it out. Now with a precise hand, poke dice holes in it. The one is in the middle, the two is diagonal as is the three. The four is secluded to corners, the five is as same as the four but with a hole in the middle and the six has two dots going down three times. You probably already knew that, but I wanted to say it just in case :) Keep it a bit shallow when you are poking your holes, cause deep holes don't actually look like real dice,I found that out on my own.
Now make sure it is square again, and mostly even and bake it or let it air dry. With the extra clay you chopped off you can make about three more dice, you just keep rolling it up and molding until there is none left :)
When it is done drying/baking, you can paint it, unless it is fimo, then it doesn't need paint. But yeah, paint it all over with your base color, let that dry, with a skinny brush paint in the holes carefully but it is ok to mess up, let that dry, and then with the skinny brush paint over any imperfections you would like to, and try to resist the holes :) You know I always love comments and versions :)