Well, the obvious happened. I liked StefanHH's ball and socket (5578), but was astonished to see no actual helping hands design on thingiverse, (my apology if I somehow missed an existing design). So I decided to design one.

You will need a base, here in the USA I used a 3 inch x 3/8 (inside diameter) iron pipe and a matching floor flange. They are nice and heavy. Elsewhere you may need to use different, but similar things. If the dimensions of your mount is different than the ones I used, don't despair, I have included some openscad files to help you out. I designed the pipemount and base_flange in Alibre, and have included the source files. However I also wrote a openscad file that imports the stl files, and allows anyone to create new sizes for the important holes. See the scad files for details.

Use your favorite aligator clips. I had some from a previous project. Mine had a 4.8 mm OD tube as the back end and was a jam fit into the 5578 center hole

To attach the base_flange to the pipe mount I used 4-20x3/4 plastite self tapping screws. If you need to use different screws you should be able to change the sizes in the scad files and generate your own parts.

Print 12 of thing 5578. Print 2 base_flanges and 1 pipemount. I glued the pipemount to the pipe. Attach 10 of the 5578, 5 to each side. String a 1.75mm filament (3 mm probably fits) end-end all the way through the 10 5578 and the mount. I tensioned mine a bit. Fill the end holes with glue (I used epoxy) - don't get glue in the sockets! - The filament helps keep the assembly together. Without it it will be easy to over bend the arms and dis-engage the ball and sockets. Attach your alligator clips to the other two 5578's and snap them on. In this way you can design other holder types and replace the alligator clip with them.