[philso]

You are best to spend some time prototyping different mechanism to learn what the advantages and disadvantages of each of the general configurations. At that point, CAD can be used to work out the exact dimensions and to make drawings to communicate what you want built.

You may find some suggestions for critical dimensions by reading some of the threads on this forum. CAD, by itself, will not tell you what critical dimensions (such as ball compression) will be best for your application.