This model is design to mount under a wood desk (or some other material you can screw into) and you will nee to print a minimum of 3 but I decided it had a nicer slide with 5. 4 on the sides of the table and 1 in the back. You can have it mounted long where the tablet mounts with the short side facing you or long ways (like I show in the photos and what I did). 

Rounded edges to save your knees.