Graphodactyl Top is the ideal gimmick for all mentalism effects with written prediction.
Graphodactyl Top is THE Solution. You will have only the advantages, without the disadvantages, with this gimmick which is a modern version of the basic Nailwriter.
The possible presentations are limited only by the fruit of your imagination!
An example of use : you take a blank card and write a prediction with a marker. You put the pen on the table and give a spectator a dice to roll.
Ask the spectator to name the number out loud, and another to read what is written on the card: the prediction coincides with the number obtained by rolling the dice!
Another example of use : you hold a notepad in one hand, you ask a spectator for a phone number. Without any suspicious gestures, you show that this is what you wrote!