This is a gennerally simple office slingshot made for firing small projectiles.
First off make sure you have all your supplies. You will need:
1 Rubber Band
a base (I used notecards but a small cork bulletin board would work better)
*Optional* you could use a knife or letter opener for making holes if the thumbtacks give you trouble
Now you shall put the thumbtacks in your base. You can use your knife or letter opener to make putting the tumbtacks in easier by poking holes.
Now you just have to put your rubber band on it and enjoy. Hope this helped you and if it didn't then im sorry if it didn't work out.