Mounting the tablet or laptop could be challenging... personally I would love to mount the device the same height as my kid so I can have conversation easier. However the tablet I have is very heavy in compare to the tank platform therefore the robot is easily tilting over.
Solution is to cut the height in half and install a high torque servo to manage the "tilting angle" as shown below
The servo I pick is the high torque, low speed servo retired from my RC airplane . The widely available 9G servo is too weak for this application.
The material of the mounting pole is a combination of carbon fiber rod and aluminum square rod from home depot. Both materials can be easily cut with hand saw or band saw but you should save yourself time and money and stick with the aluminum... The only reason I use carbon fiber rod is I happened to have one hanging around and it looks cool, but it's such a pain in the axx to couple these two materials together. Again, aluminum square rod is the better choice of making the mounting pole.
and finally, I steal my wife's cutting board from the kitchen and turn it into the table for the laptop/tablet.
Next let's move on to the programming !!
To be continued....