The little RepRap style frame (which is actually pretty little compared to the Huxley it is derived from :) is nothing else but a desktop holder for my good old Galaxy Tab.

The idea was to take the vertices used for a normal 3D printer a scale them down to fit M3 or M4 threaded rods.

The hard work was done by Adrian Bowyer and JeanMarc Giacalone, who created the design of their Huxley models, RepRapPro (the source I used) and eMaker, respectively.

I just added 2 clams to support the device.

Print either the M3 or M4 plate.
I would recommend M3 for smartphones and M4 for tablets, for stability reasons ;)
Print also a set of clams (feel free to combine the plates as you like :)
Establish the dimensions for the frame, keeping in mind that the sides for equilateral triangles. Get the threaded rods from your preferred hardware store and cut them according to your design. I used a full 1 m rod, and cut out of it 9 pieces of as equal as humanly possible length.
Have some 36 Mx nuts (and optionally the same number of washers) to assemble the frame, and a couple of M3x16 screws, with their nuts (and washers if you choose this option) to attach the clams.
Then view the images or just use your imagination to assemble everything.
Please note that there will be still enough holes available for different other purposes :D