You can buy plain round mouse pads at IKEA for only € 0,50 a piece though I just used free promotional mouse pads I got 2 years ago.
Great as a gift and to use up your scrap fabric!
For this step you need a lot of room because you need to be able to work quick.
Prepare your working space. Lay newspaper over your working space and have all things needed at hand.
*note: work fast! Spray adhesive dries very quick.
Apply your spray adhesive to the pad and if necessary smooth it out with a piece of card stock. Put the newspaper with bits of glue aside (I just folded it and threw it on the floor)