MK2 heatbed adjustable spring mount

This is an adjustable heatbed spring mount for MK2 (or similar) heatbed.
The design is parametrical - it's good to set your exact holes offset and spring diameter (see parameters in SETTINGS.scad).
It lets you to adjust heatbed level with only screwdriver or hex-key (depend on chosen screw type).
You will also need non-printable materials:
- 4 (or 8 - i used 4 pairs to make it more reliable) nuts;
- 4 screws (about 30 mm long);
- 4 (or 8) washers.
I used M3 screws and nuts. So SETTINGS.scad contains parameters for M3.

in case heatbed holes has different distances from edges in x and y directions - you should point different al_hole_ofs_x and al_hole_ofs_y parameters. You will get 2 pieces mirrored - square piece and piece with corner mark.