For anyone interested in an easy to use 3D modeling program that is FREE to use; I encourage you to check out Sketchup. If you decide to go down the rabbit hole, I highly recommend viewing their free online video tutorials. These tutorials will give you a head start and expedite the learning process so that you can hit the ground running.
Sketchup has become an extremely valuable tool for woodworkers and furniture makers. It is a design tool that allows you to workout design ideas and joinery before making your first cut. I tend to use it on every project. If you decide to use the Free version “Sketchup Make”, make sure you read and understand the License Agreement before you check the “I AGREE” box… especially if you plan to sell the plans you make using the program.