When i was beginner, I used clothes peg, as holder for PCB etching. I decide to improve design. This is Universal size holder for etching which allows you to manipulate comfortably and secure with PCB and etching soluion.

I used 2x M3 100mm Rods (you can use longer or shorter rods) 5x M3 nuts

Very big advanttage of this design is that its autolocking without need of use nut.