PCB Etching - Self locking clamp for etching bath

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.