I have for many years searched for what I considered to be the perfect masturbation method. While I love my right hand, I continued seeking a hands free method that produced the best sensations. As with many homemade devices there is variation and personal taste that are involved. I'll describe my experience and encourage you to try it and experiment.
First it requires a foam couch cushion. I use one from an old couch (that is still in use and none the worse for wear as a result of my use). My cushion has a zippered cover that allows access to the foam. In the edge of the cushion (mine is about 6' thick) tear a hole that will accommodate your penis (both depth and diameter). This may take a bit of experimentation as the hole can end up too tight or loose. Into the hole I place one of the long plastic bags that my daily newspaper arrives in. I have experimented with a number of different bags and this is by far the best. I leave several inches of the bag exposed outside the foam. Into the plastic bag I put lubricant. Again this is where I have experimented a great deal and I use KY jelly diluted with a bit of water. Other means of lubrication work fine.
Lay the cushion either on another sofa, back on the same sofa, or between the other sofa cushion and frame with the plastic bag facing out. You have to get the 'vaginal' opening at the right height for you and this may require some experimentation. Now I place a condom on my penis and insert myself into the plastic bag. While the condom is optional, there is something about wearing it that makes this work better and feel wonderful.
Now hump away doggy style while reading your favorite porn. The condom catches your sperm and the bag holds the lubricant.