Like I stated in an earlier post "the hardest part of 3D printing is the part. If you can't design a part on CAD then you are left to use someone else's like the parts we have on the the "Repository" which has quite a lot and is growing.
I suggest if you are not using a CAD program to design parts then start there. Get a simple CAD program, some are free and start designing simple parts. When you can do that you will have a much better chance of being productive using 3D printing which is not really that hard to learn and you can pick up a fairly inexpensive printer to start with. You could try to find someone locally who does 3D printing and would spend some time guiding you, that is all you should need. All the parts we put on the Repository are free to use. You can even get answers from this Forum if you run into problems.