Here is a clamp that you can use with the articulating mount system. It should fit most smartphones. Print the two pieces separately. Attach a rubber band or spring to the top piece using the provided loop, then string it through the hole in the bottom of the base and tie it off or put a small screw in the hole to hold it. This should allow the clamp to hold the phone nice and snug without the need to go to the hardware store and buy a bunch of specific nuts and bolts. Use the same bolt and nut provided in the original design, as well as the same arm from the original wall mount assembly.

I used the spring out of an ink pen and a small screw that I had laying around to assemble this. I put one loop of the spring around the hoop on the end of the top piece then fished it down through the hole and pulled it through until I got the right amount of tension with my phone clipped in. Once I had the right amount of tension, I put in the screw to hold the spring in place. It works pretty slick!!