i've tried something like it where you put a glue and attach it to a little winch thing. it pulled out most of the dent but not 100%... i guess it depends where the dent is. i ended up just taking it to the shop because it wont look 100% how well it comes out. and YOU'LL KNOW that the dent is still there while to others it might not be noticeable
Dont waste your time (waiting for it to ship) or money. It doesnt work. I found a dent in my last car a few years ago and I bought one of these from Wal-Mart and it was useless. I ended up returning the suction cup and had my mechanic fix it for me.
You're either going to have to gently pop the dent out with a hammer or take it to a body shop where they will do a good job (but it'll be costly).