Been following this guy for a while and impressed at the results he achieves. https://www.artstation.com/artwork/baVAxE Basic steps here ( not a great example ) http://archive.fabacademy.org/2016/fablabtaipei/students/184/weekly/12.html The concept is simple... 1. Create a model to print in 3d, it includes adding and cutting to get the arm post and various bits a connector. 2. Print it. 3, Clean it up. 4. Make a mold of the parts with silicone molding material. 5. Cast it. ( 6. Clean up the cast and sell, or paint for limited additions! OK get to work!