There are a few different ways to go about making stopper but this is the quickest and easier DIY way I have found.
Cut a few pieces of wood about 2" long. I used a paint stir stick because that is all I could find at the moment.
Drill a whole into them about 1/3 of the way down (or up:)) This is for the screw
In the inside back of the drawer, screw it centered but close to the top. I start with the piece of wood sideways but not peeking over the top. This way I can move and rotate it to where I need once the drawer is in place.
See what's happening here…you are now able to rotate the piece of wood.
You need it down to slide the drawer in and then are able to rotate it up once inside the drawer.
I moved it up as high as it could go once inside. This will stop the drawer form coming out but you can reach in and move it down in case you need to take the drawer out all the way.