Make a template for your skateboard. You can draw around an old board, print one out online or if you are feeling confident sketch your own. You only need half as you want your board to be symmetrical.
Find the middle of the chopping board with the ruler.
Draw around your template. Flip it over along the midpoint of the board and draw the other side.
Use a scroll saw or jigsaw to cut out the skateboard.
Use a linisher or plane to smooth out the cut edge.
If you have a spokeshave you can add a radius to the edge of the board.
Use the skateboard trucks as a template for the holes. Place them along the middle of the board and space them out with tone at the front and one at the back. There are no rules to the distance between them just keep the front one close to the front and then bring the rear one in so the board has a bit of a tail.
Drill the holes for the truck bolts. Use the countersink bit on the top of the deck so the truck bolts sit flush with the deck.