GPU Support adjustable

I liked the idea of an adjustable GPU support by TriPunk. However, M5 is a bit of an overkill in my mind and I had trouble with the original sizes - my M5 screws are probably non-standard as they were not coming through into 8.39mm pocket.

Since I have a full tower PC case, I was also thinking how to grow in height given limited printing plate size and not willing to print vertically, but rather go with a horizontal layout (11x6 cm) for a quicker print.

So I did a few modifications to the original design by TriPunk as follows:
1) replaced M5 with M4,
2) added placement sockets for 6mm (diameter) 3mm height magnets at the top and at the bottom, two magnets at the top and two at the bottom,
3) added legs and outdent at the top for extra stability when growing up,
4) added an indent at the bottom to allow the same stand to be stackable up.

Both the stand and two support parts can be printed in one go horizontally. You may need to turn around the support part for better prin