This is an easy project to make from some scraps. I recommend 2x2 scraps for this project, but you could use any board you want. Just make sure the length and/or with of your cut matches the actual height of your material. This is so you have square/even dice.

Supplies

You will need:

Scraps of your material are about 2.5x longer than the height of your material.
A saw that is appropriate for your material
I recommend a miter box if you're using a hand saw
Paint and/or stain (optional)
Dremel/drill (optional)
Permanent Marker
File/Rasp or sandpaper (I recommend both) (Optional)
Square and/or ruler (optional)

Step 1: Cutting

You will need to cut your material so that when you're finished the length and with are equal to the actual height of you're material. A miter box is recommended if you are using a hand saw. You can also put a piece of paper on the floor under where you're cutting to catch sawdust for easy cleanup later.

Step 2: Edge Rounding

I choose to round the edges on my dice. I used a file on a 45-degree angle to get a rough outline of the edge. I then used sandpaper to finish up the corner and get it rounded fully.

Step 3: Painting/Staining (Optional)

I choose to paint my dice, though you could stain yours if you wanted. I ended up doing two thick coats of acrylic paint on mine to cover up the wood.

Step 4: Engraving

If you choose to engrave the numbers into the dice, I recommend you mark out the numbers with pencil x's, and then use a rounded drill bit or Dremel bit to engrave the divots for the numbers.

Step 5: Marking

I started off with the 1 side and went from there. I recommend you mark where you are going to put the dots with light penciled in x's before you go over them in permanent marker. You can also use a ruler to make an x centered by putting across diagonally and making a line across, then rotating and repeating once more.