This clip holds a pcb by its edge while you add parts, test or solder. 

The design used a spring from a clothing peg to close the clip. There are 2 version, both use the same top.

The bottom can have 6mm diameter x 2mm thick magnets installed to hold it onto a steel surface. I suggest you install one with North out and the other with South out to get better adhesion. I used epoxy to install them.

The tips have a small raised edge to help hold onto the board when you have only a mm or 2. Deep insertion will still work and the hold will remain firm, you will probably need this for testing when you apply significant pressure to the board.

For a more rigid support, use the version that has the base near the front if you have the clearance ander the PCB.

Print on their side for best strength, no support needed.

I've provided step files so that you can remix the tip for different shapes according to your workflow. You may want to increase the height if you need to accommodate large components on you PCB.

I printed 4 pairs in 38 minutes using 0.28mm height.

Need more clamping strength, put some padding under the spring tips.