The materials to make this PCB holder are aluminum, except for the threaded bar that is in iron. I used 3 types of rods: 

• Round with a diameter of 6 mm
• Squared 10 x 10 mm
• Rectangular 20 x 5 mm, that are used for the jaws

Plus the threaded bar with a diameter of 5 mm.

From the rods, i have cut several pieces:

• From the squared rod, 4 pieces that are 8 cm long
• From the rectangular, 2 pieces that are 10 cm long 
• From the round, 2 pieces 22 cm long
• From the threaded bar, one piece 24 cm long

With the drill press, i made several holes:

There are 2 holes of 6 mm made at the two edges, for the tow squared rod that have to be fixed at the round rods. There is also one hole of 5 mm in the center for the threaded for one is a blind hole.

For the other tow squared rod, that have to slide, i made 2 holes of 6.5 mm at the edges, and one rod have the 5 mm hole in the center, while the other have the thread hole in center for the threaded bar. 

I made also the same holes on the jaws and the slots to hold PCB with a V shape rasp. The jaws are connected with 2 screws of 3 mm.

The round rod are fixed to the square rod with a small grain

At the end, all the pieces are assembled.