What is the best way to: How to make an easy finger skateboard?

Available choices:
(a). Cut out a piece of cardboard, lift the edges slightly and then place some double sided tape on the top, use your fingers to ride the skateboard.
(b). Cut out a piece of cardboard, lift the edges slightly and then place some double sided tape on the bottom, use your fingers to ride the skateboard.
Answer:
(a).