Nope, everyone designs their own! You will see a few fairly common design ideas coming up pretty often, but these are generally adopted and modified a bit in each case. Every so often someone asks why there is no "reference design" published here and the simple answer is that you will never get two members of this forum to agree to it! In fact, everyone has their own priorities re size, speed, materials to cut, materials to build from, knowledge of mechanics/welding/electronics etc so designs tend to be very personal. Pinch ideas from a few other people, blend with your own ideas/prejudices/random thoughts, and roll your own!

Learning 3D CAD is a good step as it helps with the design process as well as making it easy to publish your design for constructive comment.