How would I go about cutting a wedge out of a 2x4? When I say wedge, I am talking about a door stop style wedge, the small and wide kind you jam under the door to keep it open.

i cant for the life of me figure this out!

 

With the 4" side faceing up. At the end put a line in the middle. on the side, make a mark about 6" up from the end. Now on a angle, cut from the mark on the side to the one in the middle. If you need a pic-I'll take a few

 

go with a 1:2 rise over run pitch or less. Too much angle will not have enough wedge or pinch to hold the door back. You can even modify stops to fit specific applications. Wood usually works good on cement but if there is a slick floor try adding rubber to the bottom side. (plasti dip or an old bike tube works well)