Remixed PCB Holder 1.2

Remixed Jeebo PCB Holder 1.2 with tray:
- grip helper II. (screws and nuts: 2x M3x12 + 1x M3x18 + 2x M3),
- M3 inserts in grip helper I. (for attaching grip helper II.),
- bigger holes in L/R base for fixing 12 mm rod with 3D printed knob (for M6x25 screws and nuts),
- change rod holes to 12 mm diameter.

Thanks Jeebo for great design!
For building instruction see https://www.thingiverse.com/thing:2830674